Magnetic material composition for magnetic field amplification, and magnetic material composition for ultra-high frequency absorption

Abstract

The present invention provides a magnetic material composition for magnetic field amplification having excellent magnetic field amplification characteristics, and a magnetic material composition for ultra-high frequency absorption having excellent absorption characteristics. [Solution] The present invention relates to a magnetic material composition for magnetic field amplification and a magnetic material composition for ultra-high frequency absorption, comprising a rare earth-iron-based high-frequency magnetic powder containing rare earth elements R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, on which at least a portion of the surface is coated with a phosphorus compound, and a magnetic metal and / or metal oxide.

Description

Technical Field

[0001] The present disclosure relates to a magnetic material composition for magnetic field amplification and a magnetic material composition for ultra-high frequency absorption.

Background Art

[0002] In recent years, with the miniaturization and multifunctionality of devices and the increase in the operation processing speed, the driving frequency has been increasing, and the spread of devices using high frequencies and ultra-high frequencies has been expanding steadily.

[0003] What attracts attention is the development of power devices used in the high frequency range from 1 MHz to less than 1 GHz. For example, GaN electronic devices are expected to have a large market growth in the future as devices for high frequency and high power wireless and power electronics. For the high frequency operation of GaN circuits for power electronics, not only GaN devices but also the high frequency operation of passive components are required. For example, in GaN non-contact power supply, since the frequency to be handled exceeds 10 MHz, a coil using a magnetic core material that can follow high frequencies is required. However, at present, there is no magnetic core material with excellent high frequency characteristics, so an air-core coil has to be used. Even if GaN is applied and the device is miniaturized by increasing the frequency, there is a problem that the overall circuit size increases. Furthermore, the demand and need for high frequency magnetic materials for coils, inductors, reactors, transformers, and antennas that function at frequencies in the high frequency range of 6 MHz to less than 1 GHz are also increasing.

[0004] Another area of ​​interest is the advancement of information infrastructure in the ultra-high frequency range from 1 GHz to 1 THz. 5G utilizes frequencies between 1 GHz and 10 GHz, 5G Plus between 10 GHz and 100 GHz, and 6G between 100 GHz and 1 THz. Consequently, there is a growing need for materials that absorb electromagnetic waves in this frequency range. In particular, there is a demand for materials that can absorb broadband ultra-high frequencies above 1 GHz, and even above 10 GHz—that is, ultra-high frequency absorbing materials that can be used as electromagnetic wave absorbing materials over an ultra-broadband range between 1 GHz and 1 THz.

[0005] As an example of a magnetic material for high-frequency applications, Patent Document 1 discloses a rare-earth-iron-nitrogen-based magnetic material and a rare-earth-iron-nitrogen-based magnetic material coated with a ferrite-based magnetic material. Furthermore, it also discloses electromagnetic wave absorbing materials, etc., that include this high-frequency magnetic material. Patent Document 1 also states that this high-frequency magnetic material can be mixed with metallic magnetic materials such as Fe, Ni, Co, Fe-Ni alloys, Fe-Ni-Si alloys, Sendust, Fe-Si-Al alloys, Fe-Cu-Nb-Si alloys, amorphous alloys, and oxide-based magnetic materials such as magnetite, Ni-ferrite, Zn-ferrite, Mn-Zn ferrite, Ni-Zn ferrite, garnet-type ferrites, and soft magnetic hexagonal magnetoplanbite-based ferrites.

[0006] Furthermore, Patent Document 2 discloses magnetic materials for magnetic field amplification and magnetic materials for ultra-high frequency absorption, comprising a phosphorus compound and a rare-earth-iron-nitrogen-based magnetic powder of a specific composition. Patent Document 3 discloses magnetic materials for magnetic field amplification and magnetic materials for ultra-high frequency absorption, comprising an α-Fe-containing rare-earth-iron-nitrogen-based magnetic powder having a core region comprising rare-earth elements R, Fe, and N of a specific composition, and an α-Fe-containing region outside the core region comprising α-Fe and at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare-earth elements R. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2008 / 136391 [Patent Document 2] International Publication No. 2023 / 090220 [Patent Document 3] International Publication No. 2024 / 038829 [Overview of the project] [Problems that the invention aims to solve]

[0008] One embodiment of the present invention aims to provide a magnetic material composition for magnetic field amplification having excellent magnetic field amplification characteristics. Another embodiment of the present invention aims to provide a magnetic material composition for ultra-high frequency absorption having excellent absorption characteristics. [Means for solving the problem]

[0009] A magnetic material composition for magnetic field amplification according to one embodiment of the present invention comprises a rare earth-iron-based high-frequency magnetic powder containing rare earth elements R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, with at least a portion of its surface coated with a phosphorus compound, and a magnetic metal and / or metal oxide. Furthermore, another embodiment of the present invention provides a magnetic material composition for ultra-high frequency absorption comprising a rare-earth-iron-based high-frequency magnetic powder containing rare earth elements R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, with at least a portion of its surface coated with a phosphorus compound, and a magnetic metal and / or metal oxide. However, "high-frequency magnetic powder" means a powder of a magnetic material in which, in the frequency range of 1 MHz or more and less than 1 GHz, there exists a region in which the real term (μ') of the complex relative permeability (μ) is greater than 1, preferably greater than 2, and in the frequency range of 1 GHz or more and less than 1 THz, there exists a region in which the imaginary term (μ") of the complex relative permeability (μ) is greater than 0. [Effects of the Invention]

[0010] According to one embodiment of the present invention, a magnetic material composition for magnetic field amplification having excellent magnetic field amplification characteristics can be provided. Furthermore, according to another embodiment of the present invention, a magnetic material composition for ultra-high frequency absorption having excellent absorption characteristics can be provided. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described in detail below. However, the embodiments shown below are merely examples for realizing the technical concept of the present invention, and the present invention is not limited to these. In this specification, numerical ranges indicated using "~" represent a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively.

[0012] In this specification, "high frequency" refers to electromagnetic waves with high frequencies, and unless otherwise specified, it refers particularly to electromagnetic waves between 1 MHz and less than 1 GHz. In this specification, "ultra-high frequency" refers to electromagnetic waves with frequencies higher than high frequency, and unless otherwise specified, it refers particularly to electromagnetic waves between 1 GHz and 1 THz.

[0013] In this specification, "magnetic field amplification" refers to the characteristic in which the real term (μ') of the complex relative permeability (μ) of a magnetic material is greater than 1, which is the real term of the relative permeability of a vacuum, thereby increasing the magnetic field in the space in which the magnetic material is placed compared to the case of a vacuum (or atmosphere). "Good magnetic field amplification" or "high magnetic field amplification" at a certain frequency f means that μ' is high at that frequency f. Furthermore, a material in which μ' exceeds 2 at a certain frequency f is referred to as a "magnetic material for magnetic field amplification" (at that frequency f).

[0014] Regarding magnetic materials for magnetic field amplification and their magnetic field amplification characteristics, an increase in μ' is also referred to as "improvement of μ'," while a decrease in μ' is also referred to as "deterioration of μ'."

[0015] In this specification, "small loss" or "low loss" in magnetic field amplification characteristics means that at a certain frequency f, the imaginary term (μ'') of the complex relative permeability (μ) of the magnetic material is low. With respect to magnetic field amplification characteristics, a decrease in μ'' is also referred to as "improvement of μ''", while an increase in μ'' is also referred to as "deterioration of μ''.

[0016] Furthermore, in this specification, "excellent efficiency," "high efficiency," or "superior efficiency" in magnetic field amplification characteristics means that, at a certain frequency f, the ratio of the imaginary term (μ") to the real term (μ') of the complex relative permeability (μ) of the magnetic material, i.e., tanδ = μ'' / μ' (also called the "loss coefficient"), takes a small value. Here, δ is called the phase difference. The value of (90°-δ) is called the phase angle θ. Therefore, "excellent efficiency" means that the phase difference δ takes a small value, close to 0°, and the phase angle θ takes a large value, close to 90°. By having small tanδ and δ, or a large phase angle θ that approaches 90°, it is possible to amplify electromagnetic waves at frequency f while reducing their loss. Regarding magnetic field amplification characteristics, an increase in the value of the phase angle θ (a decrease in the values ​​of tanδ and δ) is also referred to as "improvement of the phase angle θ (tanδ)," while a decrease in the value of the phase angle θ (an increase in the values ​​of tanδ and δ) is also referred to as "deterioration of the phase angle θ (tanδ)."

[0017] In this specification, "ultra-high frequency absorption" refers to the absorption characteristics of electromagnetic waves in the ultra-high frequency region (1 GHz to 1 THz). This refers to the characteristic where the imaginary term (μ") of the complex relative permeability (μ) and / or the imaginary term (ε") of the complex relative permittivity (ε) of the magnetic material is greater than 0 in the ultra-high frequency region, thereby attenuating high frequencies incident on the space in which the magnetic material is placed. "Good (ultra-high frequency) absorption characteristics," "high (ultra-high frequency) absorption characteristics," or "excellent absorption characteristics" at a certain frequency f means that μ'' and / or ε'' are high at that frequency f, in particular, that the sum of μ'' and ε'' is high. Furthermore, materials in the ultra-high frequency region where μ'' exceeds 0 are generally called "ultra-high frequency absorption magnetic materials." In applications aimed at absorbing high-frequency magnetic field components, such as electromagnetic noise absorbers, a high ε'' is not required; rather, a high μ'' is primarily required. Therefore, "good (ultra-high frequency) absorption characteristics," "high (ultra-high frequency) absorption characteristics," or "excellent absorption characteristics" at a certain frequency f may sometimes mean that the imaginary term μ'' of the complex relative permeability is high at that frequency f. In particular, the "ultra-high frequency absorbing magnetic material" of this embodiment has μ'' greater than 0.

[0018] Regarding magnetic materials for ultra-high frequency absorption and their ultra-high frequency absorption properties, an increase in μ'' is also referred to as "improvement of μ''," while a decrease in μ'' is also referred to as "deterioration of μ''. Similarly, an increase in ε'' is also referred to as "improvement of ε''," while a decrease in ε'' is also referred to as "deterioration of ε''.

[0019] In one embodiment of this design, the magnetic field amplification characteristics in the high-frequency region (1 MHz to less than 1 GHz) are improved by increasing the real term μ' of the complex relative permeability, decreasing the imaginary term μ'' of the complex relative permeability, and decreasing the loss coefficient tanδ, among any one or more of these. Furthermore, in one embodiment of this design, the electromagnetic wave absorption characteristics, i.e., ultra-high frequency absorption characteristics, in the ultra-high frequency region (1 GHz to 1 THz) are improved by increasing the imaginary term μ'' of the complex relative permeability and increasing the imaginary term ε'' of the complex relative permittivity, among any one or more of these.

[0020] Furthermore, the magnetic field amplification characteristics in the high-frequency region and the absorption characteristics in the ultra-high-frequency region are collectively referred to as "high-frequency characteristics." Also, when simply referring to "relative permeability," it collectively refers to the absolute value of the real term μ' and the absolute value of the imaginary term μ'' of the complex relative permeability. When referring to "high relative permeability" or "high permeability," unless otherwise specified, it refers to a high real term μ' of the relative permeability.

[0021] <<Magnetic material composition for magnetic field amplification>> A magnetic material composition for magnetic field amplification according to one embodiment of the present invention comprises a rare earth-iron-based high-frequency magnetic powder (hereinafter also referred to as "phosphorus compound coated rare earth-iron-based high-frequency magnetic powder") containing rare earth element R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, with at least a portion of its surface coated with a phosphorus compound, and a magnetic metal and / or metal oxide. By adding a magnetic metal and / or metal oxide to a magnetic material composition for magnetic field amplification containing a phosphorus compound coated rare earth-iron-based high-frequency magnetic powder, the magnetic field amplification characteristics in the high-frequency region (1 MHz or more and less than 1 GHz) are improved by increasing the real term μ' of the complex relative permeability, and / or decreasing the imaginary term μ'' of the complex relative permeability, and / or decreasing the loss coefficient tanδ.

[0022] In this embodiment, the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder may be used alone or in combination of two or more types. The magnetic metal and / or metal oxide may also be used alone or in combination of two or more types. Furthermore, one or more magnetic metals may be used without using magnetic metal oxides, one or more magnetic metal oxides may be used without using magnetic metals, and one or more magnetic metals and one or more magnetic metal oxides may be used in combination.

[0023] In one embodiment of this invention, the magnetic material composition for magnetic field amplification may further contain a resin. The resin may be used alone or in combination of two or more types. Furthermore, the magnetic material composition for magnetic field amplification may also contain other components or additives as needed, as long as they do not impair the effects of this embodiment.

[0024] <Phosphorus compound-coated rare earth-iron-based magnetic powder for high-frequency applications> The high-frequency magnetic powder included in the magnetic material composition for magnetic field amplification of this embodiment is a rare-earth-iron-based high-frequency magnetic powder (phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder) containing rare earth element R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, with at least a portion of its surface coated with a phosphorus compound.

[0025] (Rare earth-iron-based magnetic powder for high-frequency applications) The rare earth-iron-based high-frequency magnetic powder according to this embodiment contains rare earth element R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe. From the viewpoint of cost, it is preferable that the rare earth element R is at least one selected from Nd, Pr, Sm, Y, Ce, and La. In one embodiment of this embodiment, it may be more preferable that the rare earth element R is Nd from the viewpoint of magnetic permeability. The total content of one or more of Nd, Pr, Sm, Y, Ce, and La relative to the total rare earth component is preferably more than 50 atomic%, more preferably 70 atomic%, even more preferably 90 atomic%, and may be 100 atomic%.

[0026] Furthermore, in addition to rare earth elements R and Fe, rare earth-iron-nitrogen-based magnetic powders are preferable because they typically have a higher real term μ' in the complex relative permeability and exhibit superior efficiency in the high-frequency region. In addition, rare earth-iron-nitrogen-based magnetic powders typically have high absorption characteristics in the ultra-high frequency region and are also preferable when applied to ultra-high frequency absorption magnetic material compositions. In rare earth-iron-nitrogen-based magnetic powders, it is preferable that the rare earth element R is at least one selected from Nd, Pr, Sm, Y, and Ce.

[0027] The composition of the rare earth-iron-based magnetic powder for high-frequency applications is given by the general formula (1) below: R x1 X 100-x1-y1 N y1 (1) An example of a rare-earth-iron-nitrogen magnetic material is a rare-earth-iron-nitrogen magnetic material consisting of a rare earth element R, a ferromagnetic component (X), and nitrogen (N), represented by the formula shown. Here, x1 and y1 are each in atomic percent. x1 is preferably 3 to 30, and more preferably 3 to 15. y1 is preferably 2 to 30, and more preferably 2 to 25. X is at least one selected from the group consisting of Fe, Co, and Ni, provided that X includes Fe, and the total amount of Co and Ni is preferably 50 atomic percent or less, and may be 1 atomic percent or less, relative to the total amount of Fe, Co, and Ni. When Co is present in an amount of 1 atomic percent or more, the Curie point tends to be higher and the thermal properties tend to be higher. When Ni is present in an amount of 1 atomic percent or more, the oxidation resistance tends to be higher. Hereinafter, Fe, Co, and Ni may be referred to as "component X".

[0028] The composition of the rare earth-iron-based magnetic powder for high-frequency applications is given by the general formula (2) below: R x2 X 100-x2-y2-z2 M y2 N z2 (2) Examples of the rare earth-iron-nitrogen magnetic material composed of a rare earth R, a ferromagnetic component (X), an M component, and nitrogen (N) represented by the following formula. Here, x2, y2, and z2 are each in atomic %. x2 is preferably 2 or more and 24 or less, more preferably 2 or more and 15 or less. y2 is preferably 0.0001 or more and 25 or less, more preferably 0.5 or more and 25 or less. z2 is preferably 2 or more and 50 or less, more preferably 3 or more and 50 or less. X is the same as in the above formula (1) and is at least one selected from the group consisting of Fe, Co, and Ni. However, X contains Fe, and the total amount of Co and Ni is preferably 50 atomic % or less, and may be 1 atomic % or less with respect to the total amount of Fe, Co, and Ni. M is at least one selected from the group consisting of Ti, V, Mo, Nb, W, Si, Al, Mn, and Cr (hereinafter also referred to as "M component"). A rare earth-iron-nitrogen magnetic material having in-plane magnetic anisotropy and a tetragonal crystal structure usually contains these M components.

[0029] When the composition of the rare earth-iron-based magnetic powder for high frequency is the above formula (1) or (2), the real part μ' of the complex relative permeability is high, tanδ is low, and good magnetic field amplification characteristics can be obtained.

[0030] As the crystal structure of the rare earth-iron-nitrogen magnetic material (magnetic powder for high frequency) having the compositions of the above formulas (1) and (2), there are Th2Zn 17 type, Th2Ni 17 type, ThMn 12 type. In any case, since μ' is high and good magnetic field amplification characteristics can be obtained, it is preferably an in-plane anisotropic material. Also, when applied to a magnetic material composition for ultra-high frequency absorption, since it becomes a broadband absorption material in the ultra-high frequency region, it is preferably an in-plane anisotropic material.

[0031] The preferred rare earth component (R) may be different for each crystal structure. In the rhombohedral Th2Zn 17 type, the rare earth R is preferably Ce, Pr, Nd, Eu, Gd, and Tb. In the hexagonal Th2Ni 17In this type, the rare earth element R is preferably Y, Dy, Ho, Er, Tm, and Lu. Tetragonal ThMn 12 In this type, the rare earth element R is preferably Sm, Er, Tm, Y, Ce, Eu, Gd, or Lu.

[0032] Furthermore, if a rare-earth-iron-nitrogen magnetic material containing nitrogen (N) is used, a magnetic material with good magnetic field amplification characteristics (magnetic material for magnetic field amplification) can be realized even in an amorphous state. In this case, light to medium rare earth elements such as Y, La, Ce, Pr, Nd, and Sm are preferred as the rare earth element R.

[0033] As mentioned above, the rare earth element R is generally preferred to be at least one selected from Nd, Pr, Sm, Y, and Ce, from the viewpoint of cost and permeability.

[0034] The composition of the rare earth-iron-based high-frequency magnetic powder is given by the general formula (3) below: R x3 X 100-x3 (3) Examples include rare-earth-iron magnetic materials, represented by the formula (1) above, which consist of a rare-earth element R and a ferromagnetic component (X). Here, x3 is in atomic percent. x3 is preferably between 2 and 33, and more preferably between 5 and 15. X is the same as in formula (1) above, and is at least one selected from the group consisting of Fe, Co, and Ni, wherein X includes Fe, and the total amount of Co and Ni is preferably 50 atomic percent or less, and may be 1 atomic percent or less, relative to the total amount of Fe, Co, and Ni.

[0035] In the case of a rare-earth-iron-based magnetic material (magnetic powder for high-frequency applications) having the composition of formula (3) above, and not containing nitrogen (N), boron (B), and carbon (C), its crystal structure is Th2Zn 17 type, Th2Ni 17 Type, ThMn 12 Examples include the type. In all cases, it is preferable that the material is an in-plane anisotropic material in that it has a high μ'.

[0036] In the case of rare-earth-iron-based magnetic materials (magnetic powders for high-frequency applications) having the composition of formula (3) above, the preferred rare-earth component (R) differs for each crystal structure. Rhombohedral Th2Zn 17 In this type, the rare earth element R is preferably Ce, Pr, Nd, Eu, Gd, Tb, and Sm. Hexagonal Th2Ni 17 In this type, the rare earth element R is preferably Y, Dy, Ho, Er, Tm, and Lu. Tetragonal ThMn 12 In this type, the rare earth element R is preferably Tb, Y, Ce, Eu, Gd, or Lu.

[0037] The composition of the rare earth-iron-based magnetic powder for high-frequency applications is given by the general formula (4) below: R x4 X 100-x4-y4 B y4 (4) An example of a rare-earth-iron magnetic material is a rare-earth element R, a ferromagnetic component (X), and boron (B), represented by the formula (1) above. Here, x4 and y4 are atomic percent. x4 is preferably 2 to 30, and more preferably 3 to 15. y4 is preferably 2 to 30, and more preferably 3 to 15. X is the same as in formula (1) above, and is at least one selected from the group consisting of Fe, Co, and Ni, provided that X includes Fe, and the total amount of Co and Ni is preferably 50 atomic percent or less, and may be 1 atomic percent or less, relative to the total amount of Fe, Co, and Ni. In addition, the M component (at least one selected from the group consisting of Ti, V, Mo, Nb, W, Si, Al, Mn, and Cr) may be substituted in the range of 0.0001 atomic percent to less than 50 atomic percent of X. When a rare-earth-iron magnetic material having a tetragonal crystal structure contains these M components, it becomes a material with a high real term μ' of complex relative permeability.

[0038] In the case of rare-earth-iron-based magnetic materials (magnetic powders for high-frequency applications) having the composition of formula (4) above, including boron (B), it is preferable that they be in-plane anisotropic materials in that they have a high μ'. Also, for example, tetragonal Nd2Fe 14 In type B, the rare earth component (R) is preferably Sm, Er, and Tm.

[0039] The composition of the rare earth-iron-based magnetic powder for high-frequency applications is given by the general formula (5) below: R x5 X 100-x5-y5-z5 N y5 C z5 (5) Examples include rare-earth-iron magnetic materials consisting of rare earth element R, a ferromagnetic component (X), and carbon (C), or rare-earth-iron-nitrogen magnetic materials consisting of rare earth element R, a ferromagnetic component (X), nitrogen (N), and carbon (C). Here, x5, y5, and z5 are each in atomic percent. x5 is preferably 3 to 30, and more preferably 3 to 15. y5 + z5 is preferably 2 to 30, and more preferably 2 to 25. y5 / z5 is preferably 0 to 10000, and more preferably 0 to 1000. X is the same as in formula (1) above, and is at least one selected from the group consisting of Fe, Co, and Ni, wherein X includes Fe, and the total amount of Co and Ni is preferably 50 atomic percent or less, and may be 1 atomic percent or less, relative to the total amount of Fe, Co, and Ni. Furthermore, the M component (at least one selected from the group consisting of Ti, V, Mo, Nb, W, Si, Al, Mn, and Cr) may be substituted in the range of 0.0001 atomic% to less than 50 atomic% of X. Rare-earth-iron-based magnetic materials or rare-earth-iron-nitrogen-based magnetic materials of formula (5) above, which have in-plane magnetic anisotropy and a tetragonal crystal structure, usually contain these M components. As mentioned above, not only formula (5) above, but also the rare-earth-iron-based magnetic materials or rare-earth-iron-nitrogen-based magnetic materials of formulas (1) to (4) above have a tetragonal crystal structure, but they do not necessarily have to contain the M component, and in particular the rare-earth-iron-based magnetic material of formula (4) above usually has a tetragonal crystal structure by containing boron (B).

[0040] When the composition of the rare-earth-iron-based high-frequency magnetic powder is as shown in formula (5) above, the real term μ' of the complex relative permeability is high, tanδ is low, and good magnetic field amplification characteristics can be obtained.

[0041] In the case of rare-earth-iron-based magnetic materials or rare-earth-iron-nitrogen-based magnetic materials (magnetic powders for high-frequency applications) having the composition of formula (5) above, it is preferable that they be in-plane anisotropic materials in that they have a high μ'. Furthermore, the preferred rare-earth component (R) for each crystal structure is the same as that of the rare-earth-iron-nitrogen-based magnetic materials having the compositions of formulas (1) and (2) above. As nitrogen is replaced by carbon, the real term μ' of the complex relative permeability and the Curie point decrease, but the heat resistance tends to improve.

[0042] The rare-earth-iron-based high-frequency magnetic powder according to this embodiment may consist of any of the high-frequency magnetic materials of formulas (1) to (5) above, or other high-frequency magnetic materials. However, as described above, it is particularly preferable that the high-frequency magnetic powder consists of a high-frequency magnetic material that further contains N (nitrogen) in addition to the rare earth elements R and Fe, i.e., a rare-earth-iron-nitrogen-based high-frequency magnetic powder. With a rare-earth-iron-nitrogen-based high-frequency magnetic powder, excellent magnetic field amplification characteristics are usually obtained in the high-frequency region (1 MHz or more and less than 1 GHz), and excellent absorption characteristics (ultra-high frequency absorption characteristics) are obtained in the ultra-high frequency region (1 GHz or more and less than 1 THz). Furthermore, in one embodiment of this embodiment, it is even more preferable that the rare-earth-iron-based high-frequency magnetic powder is an Nd-Fe-N-based high-frequency magnetic powder containing Nd, Fe, and N.

[0043] The average particle size of the rare-earth-iron-based high-frequency magnetic powder according to this embodiment is not particularly limited, but when applied to a magnetic material composition for magnetic field amplification, it is preferable to have an average particle size of 0.1 μm or more and 100 μm or less. In one embodiment of this embodiment, it may be more preferable that the average particle size of the rare-earth-iron-based high-frequency magnetic powder be 0.5 μm or more and 50 μm or less. If the average particle size of the rare-earth-iron-based high-frequency magnetic powder is less than 0.1 μm, the amount of magnetic powder filling in the molded body becomes small, which may cause the real term μ' of the complex relative permeability in the high-frequency region to decrease, and as a result, the magnetic field amplification characteristics of the resulting molded body (magnetic material composition for magnetic field amplification) may decrease. Furthermore, when applied to magnetic material compositions for ultra-high frequency absorption, if the average particle size of the rare-earth-iron-based high-frequency magnetic powder is less than 0.1 μm, the amount of magnetic powder filling in the molded body becomes small, which may cause the imaginary term μ'' of the complex relative permeability at ultra-high frequencies to decrease. As a result, the ultra-high frequency absorption characteristics of the resulting molded body (magnetic material composition for ultra-high frequency absorption) may decrease. When the average particle size of the rare-earth-iron-based high-frequency magnetic powder exceeds 100 μm, the real term μ' of the complex relative permeability tends to decrease due to the skin effect in the high-frequency region of 1 MHz or higher. Similarly, when applied to magnetic material compositions for ultra-high frequency absorption, if the average particle size of the rare-earth-iron-based high-frequency magnetic powder exceeds 100 μm, the imaginary term μ'' of the complex relative permeability tends to decrease. Here, the average particle size refers to the median diameter measured under dry conditions using a laser diffraction particle size distribution analyzer. In other words, the average particle size is represented by D50, where D50 is the particle size that corresponds to 50% of the cumulative value of the volume-based particle size distribution of the rare earth-iron-based high-frequency magnetic powder.

[0044] As the particle size of rare-earth-iron-based high-frequency magnetic powder increases, eddy currents begin to be generated within the particles from low frequencies due to the skin effect. Therefore, the larger the particle size, the more likely it is that the real term μ' of the complex relative permeability will begin to decrease from the low-frequency region. In other words, reducing the particle size of rare-earth-iron-based high-frequency magnetic powder tends to maintain high magnetic field amplification characteristics up to high frequencies. Accordingly, for magnetic materials used for magnetic field amplification, it is preferable to set the upper limit of the average particle size to be near the particle size of the rare-earth-iron-based high-frequency magnetic powder at which the real term μ' of the complex relative permeability begins to decrease at the desired frequency f0 (Hz). On the other hand, if the particle size of rare-earth-iron-based high-frequency magnetic powder becomes too small, in addition to the amount of magnetic powder filling in the molded body decreasing, the specific surface area increases as the particle size decreases, so the real term μ' of the complex relative permeability of the resulting molded body (ultra-high frequency magnetic material composition) tends to decrease. Therefore, the lower limit of the average particle size of the rare-earth-iron-based high-frequency magnetic powder is preferably around 0.1 μm, regardless of frequency. Due to the above trade-offs, it is preferable to appropriately select the particle size and average particle size of the rare-earth-iron-based high-frequency magnetic powder according to the frequency band targeted by the magnetic material composition for magnetic field amplification. Similarly, in the case of magnetic material compositions for ultra-high frequency absorption, it is preferable to appropriately select the particle size and average particle size of the rare-earth-iron-based high-frequency magnetic powder according to the frequency band targeted by the magnetic material composition for ultra-high frequency absorption.

[0045] (Phosphorus compound coated area) In this embodiment, the rare-earth-iron-based magnetic powder for high-frequency applications has at least a portion of its surface coated with a phosphorus compound. That is, in this embodiment, the rare-earth-iron-based magnetic powder for high-frequency applications has a phosphorus compound coating on at least a portion of its surface.

[0046] In this embodiment, the rare-earth-iron-based high-frequency magnetic powder is preferably coated with a phosphorus compound on at least a portion, preferably all, of its surface in order to improve oxidation resistance and to electrically insulate it from other rare-earth-iron-based high-frequency magnetic powders, or from coexisting magnetic metals (hereinafter also referred to as metal-based magnetic material powders) and / or magnetic metal oxides (hereinafter also referred to as metal oxide-based magnetic material powders). Magnetite is an example of a metal oxide-based magnetic material powder with electrical conductivity as high as graphite, and when magnetite is used, the effect of electrical insulation by the phosphorus compound coating tends to be greater. Normally, magnetic material compositions for magnetic field amplification are pressurized during molding, but if high-frequency magnetic powders come into contact with each other, or with metal-based magnetic material powders or metal oxide-based magnetic material powders, a large eddy current loss occurs, the real term μ' of the complex relative permeability decreases significantly, and the magnetic field amplification characteristics deteriorate. Furthermore, when applied to magnetic material compositions for ultra-high frequency absorption, if high-frequency magnetic powders come into contact with each other, or with metallic magnetic material powders or metal oxide magnetic material powders, and conduction occurs, the absorption characteristics in the ultra-high frequency range tend to deteriorate. The high electrical resistivity of the phosphorus compound coats the surface of the rare-earth-iron high-frequency magnetic powder, maintaining electrical insulation between the powders. In addition, even if the pressure applied during the molding of the bulk magnetic material is increased to increase the packing density, the appropriate softness of the phosphorus compound suppresses the occurrence of cracks and fissures in the rare-earth-iron high-frequency magnetic powder and its coating, and tends to maintain electrical insulation between the rare-earth-iron high-frequency magnetic powders, and furthermore, between the rare-earth-iron high-frequency magnetic powder and metallic magnetic material powders and / or metal oxide magnetic material powders.

[0047] Here, it is important that the rare-earth-iron high-frequency magnetic powder is coated with a moderately soft material that is neither as hard as a transition metal oxide such as ferrite, nor as soft as a resin, nor as soft as a phosphorus compound with fine crystals, or is amorphous. In other words, if the coating is made of a hard material such as a transition metal oxide such as ferrite or silicon oxide, the coating may break under pressure, cracks may occur in the ferromagnetic part (core region) of the rare-earth-iron high-frequency magnetic powder, or strain energy may accumulate and not be released, which tends to worsen the magnetic field amplification characteristics in the high-frequency region and the absorption characteristics in the ultra-high-frequency region. Conversely, if the coating is made of a material that is too soft, such as a resin, stress concentrates at the edges of the magnetic powder under pressure, the coating breaks, the core region is exposed, and the core regions of the magnetic powder come into direct contact with each other, making it impossible to maintain electrical insulation. Furthermore, if further pressure is applied thereafter, cracks and strains may occur in the magnetic powder, which tends to worsen the magnetic field amplification characteristics in the high-frequency region and the absorption characteristics in the ultra-high-frequency region.

[0048] Furthermore, the effect of the moderate softness of phosphorus compounds is particularly pronounced in nitride-based rare-earth-iron-nitrogen-based high-frequency magnetic materials. Soft metallic magnetic powders, such as pure iron powder with a high number of free electrons, are less prone to deformation of the magnetic material portion, even when a hard coating is applied and high pressure is exerted, thus preventing defects, cracks, or fissures that would degrade the magnetic properties of the magnetic powder. Conversely, electrically insulating materials like ceramics, which lack free electrons, do not require insulating coatings in the first place, and because they are hard, crystal deformation that would worsen magnetic properties under pressure is less likely to occur. When applied to nitride-based rare-earth-iron-nitrogen-based high-frequency magnetic powders, which have a free electron count intermediate between metals and ceramics, as well as intermediate electrical resistivity and softness between metals and ceramics, a moderately soft coating such as a phosphorus compound is very effective in improving and maintaining magnetic properties.

[0049] In addition, when a magnetic material composition containing metal oxide magnetic material powders such as ferrites with high hardness, along with rare earth-iron-based high-frequency magnetic powder without a phosphorus compound coating, is molded under high pressure to increase the packing density, strain and cracks may occur in the core region of the rare earth-iron-based high-frequency magnetic powder and the α-Fe-containing region described later, resulting in insufficient magnetic field amplification characteristics in the high-frequency region and absorption characteristics in the ultra-high-frequency region. However, if a low-hardness phosphorus compound coating is present on the surface of the rare earth-iron-based high-frequency magnetic powder, the phosphorus compound coating acts as a mechanical buffer, suppressing the occurrence of strain in the core region of the rare earth-iron-based high-frequency magnetic powder and the α-Fe-containing region even under high-pressure molding.

[0050] As described above, it is preferable that the phosphorus compound coats at least a portion of the surface of the rare-earth-iron-based high-frequency magnetic powder, as this suppresses the decrease and deterioration of μ' due to eddy current losses, as well as the deterioration of tanδ and phase angle θ, i.e., the decrease in efficiency, by providing electrical insulation not only between the rare-earth-iron-based high-frequency magnetic powders themselves, but also between the high-frequency magnetic powder and metal-based magnetic material powder or metal oxide-based magnetic material powder. The surface coating rate of the rare-earth-iron-based high-frequency magnetic powder with the phosphorus compound is preferably 10% or more, more preferably 50% or more, and even more preferably 80% or more. When the surface coating rate is 10% or more, eddy currents generated between grains are sufficiently suppressed, and the effect of reducing eddy current losses as described above is obtained. The surface coverage rate of rare-earth-iron-based high-frequency magnetic powder by phosphorus compounds can be determined by observing the cross-section of the rare-earth-iron-based high-frequency magnetic powder with a TEM, STEM, or SEM equipped with an EDS. The ratio of the length of the contact portion of the phosphorus-containing coating (phosphorus compound coating) to the total circumference of the observed surface of the rare-earth-iron-based high-frequency magnetic powder is defined as the "surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder by phosphorus compounds." It is preferable to determine the surface coverage rate for 20 to 50 cross-sections of high-frequency magnetic powders from the images observed using the above method, and to use the average value as the "surface coverage rate" of the high-frequency magnetic powder in question.

[0051] In one embodiment of this invention, it is preferable that the phosphorus compound coating completely covers the surface of the rare-earth-iron-based high-frequency magnetic powder, that is, that the surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder by the phosphorus compound is 100%. When the surface coverage rate is 100%, depending on the composition, crystal structure, and particle size of the high-frequency magnetic powder, the insulation between the rare-earth-iron-based high-frequency magnetic powders themselves, or between the rare-earth-iron-based high-frequency magnetic powders and metal-based magnetic material powders or metal oxide-based magnetic material powders, etc., is further increased. As a result, the effect of reducing eddy current losses as described above is further enhanced, and in particular, tanδ and phase angle θ are further improved in the high-frequency region, and as a result, a magnetic powder for magnetic field amplification with higher efficiency can be obtained.

[0052] The thickness of the phosphorus compound coating is preferably 1 nm to 200 nm, and more preferably 3 nm to 150 nm, from the viewpoint of improving the tanδ and phase angle θ of the high-frequency magnetic material in the high-frequency range. The thickness of the phosphorus compound coating can be measured by performing compositional analysis by line analysis, surface analysis, or point analysis by EDS in TEM, STEM, or SEM observation of the cross-section of the rare-earth-iron-based high-frequency magnetic powder.

[0053] As described later, in one embodiment of this invention, an α-Fe-containing region may exist between the rare earth-iron-based high-frequency magnetic powder and the phosphorus compound coating, comprising α-Fe (however, X and / or M components may be included in the range in which the α structure is maintained; the same applies hereinafter) and at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth R (however, X and / or M components may be included in an amount not exceeding the total content of R component; the same applies hereinafter). Furthermore, an iron oxide-containing region containing magnetite (Fe3O4) and / or maghemite (γ-Fe2O3) may exist on (outside) the phosphorus compound coating. In that case, if the thickness of the phosphorus compound coating is 10 nm or less, the α-Fe-containing region and the iron oxide-containing region will be ferromagnetically coupled with the phosphorus compound coating. This magnetic coupling will reduce the local demagnetizing field, further weakening the demagnetizing field acting on the rare-earth-iron-based high-frequency magnetic powder, which may increase the real term μ' of the complex relative permeability.

[0054] The phosphorus compound constituting the phosphorus compound coating can be any compound containing phosphorus (P), and is preferably one that can form a mechanically flexible coating. Specifically, examples of phosphorus compounds include inorganic phosphoric acids such as orthophosphoric acid, pyrophosphoric acid, and polyphosphoric acid, and phosphorus compounds such as phosphates of these inorganic phosphoric acids with Na, Ca, Pb, Zn, Fe, Co, Ni, rare earth element R, ammonium, Mo, W, V, Cr, Ti, Nb, Mn, Al, Si (hereinafter, these metal elements and atomic groups (ammonium) are also referred to as "phosphate forming components"). Furthermore, examples of phosphorus compounds constituting the phosphorus compound coating include phosphorus-containing compounds containing at least one selected from the group consisting of rare earth element R, X component (Fe, Co, Ni), and phosphate forming components, and phosphorus (P). In addition, examples of phosphorus-containing compounds containing at least one selected from the group consisting of rare earth element R, X component (Fe, Co, Ni), and phosphate forming components, and phosphorus (P) and N are also included. The phosphorus-containing compound may be, for example, a phosphorus-containing compound having an amorphous structure, known as a "phosphorus-containing amorphous compound," or a phosphorus-containing compound having a nanocrystalline structure, known as a "phosphorus-containing nanocrystalline compound." Here, "nanocrystalline compound" refers to a compound having fine crystals between 1 nm and less than 1 μm, and a phosphorus compound containing fine crystals less than 1 nm is considered an amorphous compound that does not have a nano-sized microcrystalline structure, i.e., an "amorphous compound." The crystallinity of the phosphorus compound coating and the diameter of the fine crystals in the phosphorus compound coating can be confirmed by lattice image observation using TEM and analysis using an ED (electron diffraction) device attached to the TEM apparatus.

[0055] Furthermore, the phosphorus compound coating does not have to have a constant composition, and may contain multiple phases with different compositions, and may be composed of a phosphorus-containing material or phosphorus-containing phase and a phosphorus-free material or phosphorus-free phase.

[0056] As the phosphorus compound constituting the phosphorus compound coating, phosphates and the phosphorus-containing compounds described above are preferred in that the surface coating of the rare earth-iron-based high-frequency magnetic powder becomes dense, and "phosphorus-containing amorphous compounds" and "phosphorus-containing nanocrystalline compounds" are more preferred in that the surface coating has a moderate softness. Here, the "phosphorus-containing nanocrystalline material" may be a phosphate of rare earth R, or may be in a eutectic or mixed crystal state containing at least one selected from the group consisting of a phosphate of component X (Fe, Co, or Ni) and a phosphate formed by the bonding of a phosphate-forming component and phosphoric acid, and a phosphate of rare earth R. When the phosphorus compound coating contains a "phosphorus-containing nanocrystalline compound," thermal stability may be further improved. In the production of bonded magnetic materials (composite materials of magnetic materials and resins) described later, even when high heat is applied during the kneading, molding, and thermosetting processes, the magnetic properties of the rare-earth-iron-based high-frequency magnetic powder, such as magnetic field amplification characteristics in the high-frequency range and absorption characteristics in the ultra-high-frequency range, tend to deteriorate less. As a result, the final molded product may have high thermal stability and excellent efficiency.

[0057] The average atomic concentration of phosphorus (P) in the phosphorus compound coating is preferably 0.1 atomic% or more, and more preferably 0.3 atomic% or more. Furthermore, the average atomic concentration of phosphorus (P) in the phosphorus compound coating is preferably 25 atomic% or less, and more preferably 15 atomic% or less. If the average atomic concentration of phosphorus in the phosphorus compound coating is less than 0.1 atomic%, the electrical insulating properties of the phosphorus compound tend not to function well, and the effect of the phosphorus compound coating tends to be difficult to obtain. If the average atomic concentration of phosphorus in the phosphorus compound coating exceeds 25 atomic%, the real term μ' of the complex relative permeability in the high-frequency range may decrease, and the performance against corrosion resistance also tends to decrease. The average atomic concentration of phosphorus (P) in the phosphorus compound coating can be measured by performing compositional analysis by line analysis, surface analysis, or point analysis using EDS during TEM, STEM, or SEM observation of the cross-section of the rare-earth-iron-based high-frequency magnetic powder. The localized phosphorus content in rare-earth-iron-based high-frequency magnetic powders, not just in phosphorus compound-coated areas, can be measured by STEM-EDS line analysis, etc.

[0058] The phosphorus compound content in the rare earth-iron-based high-frequency magnetic powder having a phosphorus compound coating is preferably 0.001% to 4.5% by mass, more preferably 0.05% to 2.5% by mass, and even more preferably 0.1% to 2% by mass, assuming that the phosphorus compound exists as a rare earth phosphate. When the phosphorus compound content in phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder is 4.5% by mass or less, aggregation of the rare-earth-iron-based high-frequency magnetic powder tends to be further reduced, the deterioration of the real term μ' of the complex relative permeability in the high-frequency range is further suppressed, the deterioration of tanδ and phase angle θ in the high-frequency range is further reduced, and the deterioration of the imaginary term μ'' in the ultra-high frequency range also tends to be further suppressed. When the phosphorus compound content in phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder is 0.001% by mass or more, the electrical insulation of the phosphorus compound coating tends to be further improved, similarly, the deterioration of the real term μ' of the complex relative permeability in the high-frequency range is further suppressed, the deterioration of tanδ and phase angle θ in the high-frequency range is further reduced, and the deterioration of the imaginary term μ'' in the ultra-high frequency range also tends to be further suppressed.

[0059] Furthermore, the phosphorus (P) content in the rare earth-iron-based high-frequency magnetic powder having a phosphorus compound coating is preferably 0.0005% to 4% by mass, more preferably 0.001% to 2% by mass, and even more preferably 0.05% to 1% by mass. When the phosphorus content in the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder is 0.0005% by mass or more, the effect of coating by the phosphorus compound tends to be greater. When the phosphorus content in the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder is 4% by mass or less, the aggregation of magnetic powder particles starting from the phosphorus compound tends to be more suppressed, which can worsen tanδ and phase angle θ in the high-frequency region. When the phosphorus content in the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder is 0.05% to 1% by mass, a magnetic material for magnetic field amplification with particularly excellent efficiency may be obtained. Furthermore, the phosphorus content in the entire phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder can be measured using ICP-AES (ICP emission spectroscopy).

[0060] The phosphorus compound coating on the surface of the rare-earth-iron-based high-frequency magnetic powder may have a region (hereinafter also referred to as the "high-R concentration region") in which the average atomic concentration of rare-earth R is higher than the average atomic concentration of rare-earth R in the rare-earth-iron-based high-frequency magnetic powder (hereinafter also referred to as the "core region"). The average atomic concentration of rare-earth R in the high-R concentration region can be, for example, 1.05 times or more the average atomic concentration of rare-earth R in the core region, usually preferably 1.1 times or more, more preferably 1.2 times or more, and even more preferably 1.4 times or more. Furthermore, the average atomic concentration of rare-earth R in the high-R concentration region can be, for example, 4 times or less the average atomic concentration of rare-earth R in the core region. The high-R concentration region can be, for example, a region that includes the layer showing the maximum peak of P (phosphorus) in the STEM-EDS line analysis of the cross-section of the rare-earth-iron-based high-frequency magnetic powder. The thickness of the R-high concentration region can be, for example, 1 nm or more, preferably 3 nm to 150 nm, more preferably 5 nm to 100 nm, and even more preferably 7 nm to 80 nm. When the average atomic concentration of rare earth elements R in the R-high concentration region is within the above range relative to the average atomic concentration of rare earth elements R in the core region, the change in Gibbs free energy is small (the absolute negative value is large), oxidation resistance is higher, electrical resistivity is higher, and furthermore, the real term μ' of the complex relative permeability in the high-frequency region and the imaginary term μ'' in the ultra-high-frequency region tend to be higher. The average atomic concentration (atomic %) of each element in the R-high concentration region can be determined, for example, by averaging the atomic concentrations in the R-high concentration region within the phosphorus compound coating obtained by STEM-EDS line analysis. Here, the average atomic concentration of rare earth elements R is the sum of the average atomic concentrations of all rare earth elements R.

[0061] The R-high concentration region may contain not only rare earth elements R and P (phosphorus), but also components X (Fe, Co, Ni), and may also contain components M and N. The ratio R / X, which is the average atomic concentration of rare earth element R in the R-high concentration region to the average atomic concentration of component X, can be, for example, 0.05 or more, usually preferably 0.1 or more, and more preferably 0.2 or more. The upper limit of R / X in the R-high concentration region can be, for example, 100 or less, may be 20 or less, or may be 10 or less. Furthermore, R / X in the R-high concentration region may have a higher value than R / X in the core region. R / X in the R-high concentration region can be, for example, 1 or more times R / X in the core region, usually preferably 1.5 or more, more preferably 2 or more, and even more preferably 2.5 or more. When R / X in the R-high concentration region is within the above range relative to R / X in the core region, water resistance tends to improve further. Here, the average atomic concentration of rare earth elements R is the sum of the average atomic concentrations of all rare earth elements R, and the average atomic concentration of component X is the sum of the average atomic concentrations of Fe, Co, and Ni.

[0062] (Mo high concentration area) In one embodiment of this invention, the rare-earth-iron-based high-frequency magnetic powder may further have a high-Mo concentration region. The high-Mo concentration region is a region in which Mo is present at a higher concentration than the iron oxide-containing region and the α-Fe-containing region described later. The high-Mo concentration region is formed, for example, when Mo is used when forming the phosphorus compound coating, that is, when the phosphorus compound coating contains Mo. More specifically, the high-Mo concentration region is a passivation film formed by Mo, the X component of the rare-earth-iron-based high-frequency magnetic powder (core region), and oxygen (O) during the process of forming the phosphorus compound coating. For example, an effect equivalent to that obtained when the surface of the rare-earth-iron-based high-frequency magnetic powder is pre-treated with oxomolybdic acid to form a passivation film and improve corrosion resistance can be achieved simultaneously with the formation of the phosphorus compound coating simply by adding Mo during the phosphorus treatment. The high-Mo concentration region is preferably located directly above the α-Fe-containing region and / or in the phosphorus compound coating region, particularly directly above the high-R concentration region (i.e., directly below the iron oxide-containing region), and / or directly above the core region (i.e., in the phosphorus compound coating region, particularly directly below the high-R concentration region). Having a high-Mo concentration region can increase the strength of the coating layer on the rare-earth-iron-based high-frequency magnetic powder (core region), thereby improving the corrosion resistance of the core region. In particular, when the high-Mo concentration region is directly above the α-Fe-containing region, the effect of improving corrosion resistance tends to be greater. The high-Mo concentration region located directly above the high-R concentration region is pushed out of the film by R, which has no affinity for Mo and a very high affinity for P, during the oxidation treatment described later, and is formed directly below the iron oxide-containing region.

[0063] The thickness of the high-Mo concentration region is preferably, for example, 1 nm to 1 μm, and more preferably 2 nm to 100 nm. Furthermore, when a rare-earth-iron-based high-frequency magnetic powder having an α-Fe-containing region (hereinafter also referred to as α-Fe-containing rare-earth-iron-based high-frequency magnetic powder) contains a high-Mo concentration region, the thickness of the high-Mo concentration region is preferably 0.001% to 25% of the average particle size of the entire α-Fe-containing rare-earth-iron-based high-frequency magnetic powder (including the α-Fe-containing region), and more preferably 0.01% to 10%.

[0064] (α-Fe containing region) In one embodiment of this invention, an α-Fe-containing region may exist between the rare-earth-iron-based high-frequency magnetic powder (core region) and the phosphorus compound coating, the region containing α-Fe and at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R.

[0065] The α-Fe-containing region can enhance the electrical insulation between high-frequency magnetic powders, further suppressing efficiency reduction due to eddy currents across grains. The presence of the α-Fe-containing region can improve tanδ and phase angle θ, particularly in the high-frequency region, potentially yielding more efficient magnetic powders for magnetic field amplification. Furthermore, the α-Fe-containing region can magnetically connect high-frequency magnetic powders, reducing the demagnetizing field. The presence of the α-Fe-containing region can also improve the real term μ' of the complex relative permeability of rare-earth-iron-based high-frequency magnetic powders, potentially improving magnetic field amplification characteristics.

[0066] Here, the rare earth-iron-based high-frequency magnetic powder (core region) is a rare earth-iron-nitrogen-based high-frequency magnetic powder containing a rare earth-iron-nitrogen-based compound, and when an α-Fe-containing region exists between the rare earth-iron-nitrogen-based high-frequency magnetic powder (core region) and the phosphorus compound coating, the diffraction peak intensity of the (110) plane of α-Fe in the XRD diffraction pattern is (I α-Fe ) and the peak intensity of the strongest line for rare earth-iron-nitrogen compounds (I core ) ratio (I α-Fe ) / (I core The peak intensity ratio (I) is preferably 0.01 or more and less than 100, and more preferably 0.1 or more and 10 or less. α-Fe ) / (I core When this range is present, tanδ tends to remain low, especially around 100MHz, while μ' tends to improve.

[0067] The α-Fe-containing region preferably contains a compound consisting of at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R, and nanocrystals consisting of the α-Fe phase. The compound consisting of at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R is preferably a nanocrystal. That is, the α-Fe-containing region more preferably contains at least one nanocrystal selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R. The presence of at least one nanocrystal selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R can be confirmed, for example, by observing a halo near the strongest diffraction line of those compounds (for example, when the diffraction angle 2θ is around 20-30°) in XRD using a CuKα source, or by observing a ring inside the ring pattern showing the α-Fe phase in electron diffraction measured in the α-Fe-containing region.

[0068] It is believed that the electrical insulation and magnetic coupling effects of the α-Fe-containing region are enhanced when the α-Fe-containing region includes a compound consisting of at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R, and nanocrystals made of α-Fe. Here, "electrical insulation" refers to the fact that the presence of the α-Fe-containing region, which has high electrical resistance, on the surface of the high-frequency magnetic powder blocks conductivity between the high-frequency magnetic powder (core region), suppressing the generation of eddy currents across the high-frequency magnetic powder. This electrical insulation suppresses eddy current losses, resulting in excellent efficiency in magnetic field amplification characteristics. The phosphorus compound coating and the iron oxide-containing region described later also have a similar electrical insulation effect. Furthermore, "magnetic coupling" refers to the fact that the presence of the α-Fe-containing region, which has high electrical resistance but is ferromagnetic, on the surface of the high-frequency magnetic powder creates ferromagnetic or magnetostatic coupling between the high-frequency magnetic powder (core region). This magnetic coupling reduces the local demagnetizing field, weakening the demagnetizing field acting on the high-frequency magnetic powder (core region), thereby achieving a high real term μ' of the complex relative permeability.

[0069] The α-Fe-containing region may further contain, to an extent that does not impair the magnetic coupling, complex oxides, complex nitrides, complex oxynitrides, or carbonitrides containing rare earth elements R and iron (Fe), as well as other carbon-containing materials, boron-containing materials such as borides, etc. The complex oxides, complex nitrides, and complex oxynitrides may have a perovskite structure or a spinel structure.

[0070] The α-Fe phase is a cubic crystal with a bcc structure, and its main component is Fe. The α-Fe phase may also contain ferromagnetic components such as Co and Ni, and the total content of ferromagnetic components other than Fe is preferably 50 atomic percent or less. The α-Fe phase may also contain M components such as Ti, V, Mo, Nb, W, Si, Al, Mn, and Cr, as well as nitrogen, but in order not to impair the ferromagnetism of the α-Fe phase, it is preferable that the content be in an amount that does not disrupt the bcc structure. For example, when Si is included, its content is preferably 10 atomic percent or less. When nitrogen is included, its content is preferably 5 atomic percent or less. When boron is included, its content is preferably 12 atomic percent or less, and more preferably 5 atomic percent or less. When carbon is included, its content is preferably 12 atomic percent or less, and more preferably 5 atomic percent or less.

[0071] The compound included in the α-Fe-containing region, which is at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth elements R, may exist in particulate form (preferably as nanocrystals), in which case the average particle size is preferably 1 nm or more and less than 1000 nm, more preferably 1 nm or more and 100 nm, more preferably 1 nm or more and 20 nm, and even more preferably 1 nm or more and 10 nm. Fe-based nanocrystals having a bcc structure, i.e., nanocrystals consisting of the α-Fe phase, preferably have an average particle size of 1 nm or more and less than 1000 nm, more preferably 1 nm or more and 100 nm, more preferably 1 nm or more and 20 nm, and even more preferably 1.5 nm or more and 10 nm. These average particle sizes can be measured by TEM (transmission electron microscope) or STEM (scanning transmission electron microscope) on a cross-section of a rare-earth-iron-based high-frequency magnetic powder having an α-Fe-containing region (hereinafter also referred to as "α-Fe-containing rare-earth-iron-based high-frequency magnetic powder"), or by EDS (energy-dispersive X-ray analysis) attached thereto. The number of measurement points should be 20 or more, preferably 50 or more, and the average particle size is determined by arithmetic mean of these measurements. The compound phase, which is at least one selected from the group consisting of oxides, nitrides, and oxynitrides of rare earth R, and the α-Fe phase may both be particulate, or one may be particulate and the other may be a continuous phase.

[0072] Furthermore, the crystallite size of Fe-based nanocrystals with a bcc structure, i.e., nanocrystals consisting of the α-Fe phase, can sometimes be calculated using Scherrer's equation D = Kλ / βcosθ (K: Scherrer constant 0.9, λ: X-ray wavelength (nm), β: FWHM of the diffraction peak (radians), θ: Bragg angle (radians)) by using the full width at half maximum (FWHM) of the peak on the (110) plane measured by powder X-ray diffraction, provided that the crystallite size is between 1 nm and 100 nm and can be separated from the peak of the rare-earth-iron-based high-frequency magnetic powder (core region). For example, the FWHM of a crystal consisting of the α-Fe phase can be determined by measuring with a CuKα X-ray source at 40 kV and 15 mA, with a step size of 2θ = 0.01 between diffraction angles of 10 < 2θ < 90. For example, measurements taken at a wavelength where λ = 0.154 nm are used. Alternatively, the full width at half maximum (FWHM) of a crystal composed of the α-Fe phase can be determined by measuring with a CoKα X-ray source at 40kV and 135mA, with a step size of 2θ = 0.01 between diffraction angles of 20 < 2θ < 110. For example, measurements taken at a wavelength where λ = 0.179 nm are used. In this case, the crystallite size of the nanocrystal composed of the α-Fe phase, as determined by Scherrer's formula, is more preferably between 1 nm and 100 nm, more preferably between 1 nm and 20 nm, more preferably between 1 nm and 15 nm, and even more preferably between 1.5 nm and 10 nm.

[0073] The average atomic concentration of Fe in the entire α-Fe-containing region is preferably 25 atomic% or more, and more preferably 40 atomic% or more. The upper limit of the average atomic concentration of Fe is not particularly limited, but it can be 80 atomic% or less. When the average atomic concentration of Fe is 25 atomic% or more, good magnetic coupling is maintained, which tends to result in a smaller demagnetizing field and a higher real term μ' of the complex relative permeability.

[0074] The average atomic concentration of rare earth elements R in the entire α-Fe-containing region is preferably 1 atom% to 50 atoms, and more preferably 2 atoms% to 30 atoms. The average atomic concentration of nitrogen in the entire α-Fe-containing region is preferably 0 atoms% to 50 atoms, and more preferably 0.01 atoms% to 30 atoms. The average atomic concentration of oxygen in the entire α-Fe-containing region is preferably 0 atoms% to 55 atoms, and more preferably 0.01 atoms% to 40 atoms.

[0075] Furthermore, the average atomic concentration (atomic %) of each element in the α-Fe-containing region can be determined, for example, by averaging the atomic concentrations in each measurement region in STEM-EDS line analysis.

[0076] The average atomic concentration (atomic %) of oxygen in the entire α-Fe-containing region is preferably higher than the average atomic concentration (atomic %) of oxygen in the rare-earth-iron-based high-frequency magnetic powder (core region). The average atomic concentration of oxygen in the entire α-Fe-containing region is preferably 1.05 times or more, more preferably 1.5 times or more, more preferably 2 times or more, and even more preferably 2.5 times or more than the average atomic concentration of oxygen in the rare-earth-iron-based high-frequency magnetic powder (core region).

[0077] The average atomic concentration (atomic %) of rare earth elements R in the entire α-Fe-containing region is preferably 2 times or less, more preferably 1.9 times or less, and even more preferably 1.8 times or less, the average atomic concentration (atomic %) of rare earth elements R in the rare earth-iron-based high-frequency magnetic powder (core region). Furthermore, the average atomic concentration (atomic %) of rare earth elements R in the entire α-Fe-containing region is preferably 0.1 times or more, and more preferably 0.5 times or more, the average atomic concentration (atomic %) of rare earth elements R in the rare earth-iron-based high-frequency magnetic powder (core region).

[0078] Here, the average atomic concentration of a specific element (oxygen and rare earth element R) refers to the atomic concentration obtained by performing STEM-EDS line analysis on one or more line segments that penetrate in the thickness direction from the core region of the rare earth-iron-based high-frequency magnetic powder to the outermost surface of the α-Fe-containing region in a rare earth-iron-based high-frequency magnetic powder having an α-Fe-containing region, measuring the atomic concentration of the element at 10 or more points, and averaging these measured values.

[0079] The thickness of the α-Fe-containing region is preferably 0.001% or more and less than 50% of the average particle size of the α-Fe-containing rare-earth-iron-based high-frequency magnetic powder (the entire rare-earth-iron-based high-frequency magnetic powder having an α-Fe-containing region; including the α-Fe-containing region), more preferably 0.002% or more and 45%, more preferably 0.003% or more and 35%, and even more preferably 0.01% or more and 20%. When the thickness of the α-Fe-containing region is 0.001% or more of the average particle size of the α-Fe-containing rare-earth-iron-based high-frequency magnetic powder, the electrical insulation tends to improve. When the thickness of the α-Fe-containing region is less than 50% of the average particle size of the α-Fe-containing rare-earth-iron-based high-frequency magnetic powder, μ' tends to be higher due to the presence of a core region which is the rare-earth-iron-based high-frequency magnetic powder.

[0080] The thickness of the α-Fe-containing region is preferably 1 nm to 80 μm, more preferably 2 nm to 80 μm, more preferably 3 nm to 20 μm, and even more preferably 5 nm to 5 μm. Furthermore, in terms of improving μ' in the high-frequency region, the thickness of the α-Fe-containing region may be 100 nm or more, 300 nm or more, or 1 μm or less. When the thickness of the α-Fe-containing region is 1 nm or more, the electrical insulation tends to improve. When the thickness of the α-Fe-containing region is 80 μm or less, μ' tends to be higher due to the presence of a core region which is a rare-earth-iron-based high-frequency magnetic powder.

[0081] The thickness of the α-Fe-containing region can be measured by TEM, STEM, or SEM observation of a cross-section of the α-Fe-containing rare-earth-iron-based high-frequency magnetic powder (rare-earth-iron-based high-frequency magnetic powder having an α-Fe-containing region), and by performing compositional analysis using TEM images, STEM images, and secondary electron / backscattered electron images (SEM images), or by line analysis, surface analysis, or point analysis by EDS. Furthermore, regarding the average particle size of the α-Fe-containing rare-earth-iron-based high-frequency magnetic powder, the average particle size here refers to the median diameter (D50) measured under dry conditions using a laser diffraction particle size distribution analyzer, where D50 is the particle size corresponding to 50% of the cumulative value of the volume-based particle size distribution of the rare-earth-iron-based high-frequency magnetic powder.

[0082] The surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder (core region) with the α-Fe-containing region is preferably 10% or more, more preferably 50% or more, even more preferably 80% or more, and particularly preferably 100% (complete coverage). When the surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder (core region) with the α-Fe-containing region is high, the electrical insulation performance increases, tanδ and phase angle θ improve further, and there is a tendency for higher efficiency. In particular, when the surface coverage rate is 100%, the electrical isolation of the rare-earth-iron-based high-frequency magnetic powder is promoted, and the above effects may be further enhanced. The surface coverage rate of a rare-earth-iron-based high-frequency magnetic powder (core region) due to the α-Fe-containing region can be determined by observing the cross-section of the powder with a TEM, STEM, or SEM equipped with an EDS. The ratio of the length of the contact portion between the α-Fe-containing region and the rare-earth-iron-based high-frequency magnetic powder (core region) to the total circumference of the observed rare-earth-iron-based high-frequency magnetic powder (core region) is defined as the "surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder (core region) due to the α-Fe-containing region." It is preferable to determine the surface coverage rate for 20 to 50 cross-sections of high-frequency magnetic powders from the images observed using the above method, and to use the average value as the "surface coverage rate" of the high-frequency magnetic powder in question.

[0083] In this embodiment, the α-Fe-containing region may have a structure in which nanocrystals of the ferromagnetic α-Fe phase are isolated within a matrix phase of rare earth R oxide, nitride, or oxynitride (however, M component may be included in these phases; the same applies hereinafter), that is, a so-called sea (matrix phase of rare earth R oxide, nitride, or oxynitride)-island (nanocrystal of the α-Fe phase) structure. When the α-Fe-containing region has such a sea-island structure, the nanocrystals of the metallic α-Fe phase are isolated within the matrix phase of rare earth R oxide, nitride, or oxynitride, thus suppressing the occurrence of electron percolation and maintaining better electrical insulation.

[0084] In the α-Fe-containing region, it is preferable that the α-Fe phase nanocrystalline particles are arranged regularly at a high density. When the α-Fe phase nanocrystalline particles in the α-Fe-containing region are preferably arranged regularly at a high density, each α-Fe phase nanocrystalline particle is ferromagnetically or magnetostatically coupled, and magnetic flux can easily pass through the α-Fe-containing region, which tends to make the magnetic coupling more stable.

[0085] In an α-Fe-containing region having a sea-island structure including a sea region and an island region as described above, the sea region may contain the M component and / or the X component, and the island region may also contain the M component and / or the X component. For example, the α-Fe-containing region may have a sea-island structure including a sea region and an island region, and the atomic concentration (%) of the X component may be higher in the island region than in the sea region. In that case, the atomic concentration (%) of the X component in the island region is preferably 10% or more higher than the atomic concentration (%) of the X component in the sea region, and more preferably 20% or more higher. The atomic concentration (%) of each element in the island region and the sea region can be determined by averaging the atomic concentrations in each region in STEM-EDS line analysis.

[0086] The presence or absence of regularly arranged, i.e., oriented crystalline phases, as well as their size and volume fraction, can be measured, for example, by observing STEM images of the entire α-Fe-containing rare-earth-iron-based high-frequency magnetic powder (rare-earth-iron-based high-frequency magnetic powder having an α-Fe-containing region) or near its surface, or by using an ED (electron diffraction) device attached to a TEM apparatus. For example, in a STEM image of a cross-section of α-Fe-containing rare-earth-iron-based high-frequency magnetic powder, a region containing both the α-Fe phase and the oxide, nitride, or oxynitride phase of rare-earth R, with lattice fringes in one direction, is defined as an "oriented region," and image analysis is performed. Using a scanning transmission electron microscope (STEM), five locations within the region containing the α-Fe-containing region of the α-Fe-containing rare-earth-iron-based high-frequency magnetic powder (if the α-Fe-containing region is thick, it may be divided into multiple fields of view) are photographed, and the size and volume fraction of the oriented crystalline phase can be confirmed by comparing the "oriented region" with the non-oriented region within the photographed area. Furthermore, the presence or absence of oriented crystals can be confirmed by the electron diffraction pattern of the TEM-ED image. The volume fraction of nano-sized α-Fe phase in the α-Fe-containing region is preferably 5 to 95 atoms, and more preferably 10 to 90 atomic percent.

[0087] (Iron oxide-containing region) In one embodiment of this design, an iron oxide-containing region containing magnetite (Fe3O4) and / or maghemite (γ-Fe2O3) may further exist on (outside) the phosphorus compound coating or the high-Mo concentration region. The presence of a ferromagnetic iron oxide-containing region can further improve the real term μ' of the complex relative permeability of the rare-earth-iron high-frequency magnetic powder, resulting in higher efficiency and improved magnetic field amplification characteristics. It can also significantly reduce the demagnetizing field of the entire high-frequency magnetic powder. If the phosphorus compound coating does not completely cover the surface of the rare-earth-iron high-frequency magnetic powder, the iron oxide-containing region may exist on the exposed surface of the rare-earth-iron high-frequency magnetic powder. Hereafter, this configuration will also be referred to as "existing on the phosphorus compound coating."

[0088] The presence of an iron oxide-containing region can be confirmed, for example, by observing peaks in XRD using a CuKα source near the strong diffraction lines of magnetite (e.g., around 29-31° for the diffraction angle 2θ of the (220) plane and around 56-58° for the diffraction angle 2θ of the (511) plane) in regions that do not overlap with the diffraction lines of the rare-earth-iron-based high-frequency magnetic powder (core region), or near the strongest diffraction lines of maghemite (e.g., around 29-31° for the diffraction angle 2θ of the (220) plane and around 56-58° for the diffraction angle 2θ of the (511) plane).

[0089] Here, if the rare-earth-iron-based high-frequency magnetic powder (core region) is a rare-earth-iron-nitrogen-based high-frequency magnetic powder containing a rare-earth-iron-nitrogen-based compound, and an iron oxide-containing region exists above (outside) the phosphorus compound coating, then in the XRD diffraction pattern, the diffraction peak intensity of the (511) plane of magnetite and / or maghemite (I Fe3O4+γ-Fe2O3 ) and the peak intensity of the strongest line for rare earth-iron-nitrogen compounds (I core ) ratio (I Fe3O4+γ-Fe2O3 ) / (I core The peak intensity ratio (I) is preferably 0.01 or more and less than 100, and more preferably 0.1 or more and less than 100. Fe3O4+γ-Fe2O3 ) / (I core When ) is within this range, tanδ tends to remain low while μ' tends to improve.

[0090] Magnetite and maghemite have the same tetragonal spinel crystal structure and nearly identical lattice constants a (0.840 nm for magnetite and 0.835 nm for maghemite). Therefore, if the iron oxide-containing region is nanoscale in thickness, it is difficult to distinguish between them by XRD measurements. For example, it is possible to distinguish between magnetite and maghemite by measuring the valence of Fe using XPS (X-ray photoelectron spectroscopy) or by extracting EXAFS (extensive X-ray absorption fine structure) vibrations from XAFS (X-ray absorption fine structure) spectra and comparing the radial distribution functions obtained by Fourier transform.

[0091] Comparing the electromagnetic properties of maghemite and magnetite, maghemite has a volume resistivity of 10⁻¹⁰ 6 While the magnetic field is Ωm and the magnetization is 0.42T, magnetite has a volume resistivity of 4 × 10⁻¹⁶. -5 With a magnetic density of Ωm and a magnetization of 0.60T, maghemite has slightly lower magnetization than magnetite, but higher electrical resistance. Therefore, magnetite is superior in magnetic coupling, while maghemite is advantageous in electrical insulation. Consequently, to achieve efficiency superior to high permeability, the magnetite contained in the iron oxide-containing region can be oxidized and converted to maghemite by heat treatment, for example, in an oxygen-containing atmosphere, preferably at a temperature between 200°C and 600°C.

[0092] The iron oxide-containing region preferably contains magnetite and / or maghemite as its main components. In other words, it is preferable that the iron oxide-containing region does not contain hematite (α-Fe2O3), or if it contains hematite, it is not the main component.

[0093] Here, if an iron oxide-containing region exists above (outside) the phosphorus compound coating or the high Mo concentration region, the diffraction peak intensity of the (104) plane of hematite in the XRD diffraction pattern (I α-Fe2O3 ) and the diffraction peak intensity of the (511) plane of magnetite and / or maghemite (I Fe3O4+γ-Fe2O3 ) ratio (I α-Fe2O3 ) / (I Fe3O4+γ-Fe2O3 The peak intensity ratio (I) is preferably 0 or more and less than 10, and more preferably 0 or more and less than 5. α-Fe2O3 ) / (I Fe3O4+γ-Fe2O3 When the values ​​are within this range, the loss due to the electrical insulating effect of hematite is reduced, and furthermore, the magnetic coupling effect of magnetite and / or maghemite is obtained, which tends to improve the real term μ' and the imaginary term μ'' of the complex relative permeability.

[0094] Furthermore, if individual peaks cannot be identified by XRD, the presence and composition ratio of iron oxide can also be calculated from quantitative values ​​obtained by EDS in TEM, STEM, or SEM observations of the cross-section of rare-earth-iron-based high-frequency magnetic powder containing iron oxide regions.

[0095] The thickness of the iron oxide-containing region is preferably 0.01% to 10% of the average particle size of the entire rare-earth-iron-based high-frequency magnetic powder having the iron oxide-containing region (including the iron oxide-containing region from the core to the surface), and more preferably 0.05% to 2%. When the thickness of the iron oxide-containing region is within this range, the ferromagnetic coupling between the high-frequency magnetic powder particles becomes stronger, the demagnetizing field decreases, and μ' tends to increase. Furthermore, the thickness of the iron oxide-containing region is preferably greater than 0 nm and 1 μm or less, and more preferably 1 nm to 100 nm. When the thickness of the iron oxide-containing region is 1 μm or less, the decrease in μ' tends to be suppressed. The thickness of the iron oxide-containing region can be measured by performing compositional analysis by line analysis, surface analysis, or point analysis using EDS during TEM, STEM, or SEM observation of the cross-section of the rare-earth-iron-based high-frequency magnetic powder having the iron oxide-containing region.

[0096] The content of magnetite and / or maghemite in the rare-earth-iron-based high-frequency magnetic powder having an iron oxide-containing region is preferably 0.005% by mass or more and 0.15% by mass or less, and more preferably 0.01% by mass or more and 0.1% by mass or less. When the content of magnetite and / or maghemite is within this range, the iron oxide-containing region may be formed more uniformly on the surface of the rare-earth-iron-based high-frequency magnetic powder, both on the phosphorus compound coating and in areas where the phosphorus compound coating is absent.

[0097] In this embodiment, the iron oxide-containing region covers the surface of the phosphorus compound coating on the surface of the rare-earth-iron-based high-frequency magnetic powder, and in areas where the phosphorus compound coating is absent, it covers at least a portion of the exposed surface of the rare-earth-iron-based high-frequency magnetic powder. The surface coverage rate of the iron oxide-containing region is preferably 25% or more, and more preferably 75% or more. When the surface coverage rate of the iron oxide-containing region is 25% or more, μ' tends to improve further, and tanδ also tends to improve further. In one embodiment of this embodiment, it is also preferable that the surface coverage rate of the iron oxide-containing region is 100%. The surface coverage of the iron oxide-containing region (surface coverage of phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder by the iron oxide-containing region) can be determined by observing the cross-section of the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder with an EDS-equipped TEM, STEM, or SEM. The ratio of the length of the contact portion of the coating containing magnetite and / or maghemite (iron oxide-containing region) to the total circumference of the observed phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder surface is defined as the "surface coverage of the iron oxide-containing region." Preferably, the surface coverage is determined for 20 to 50 cross-sections of high-frequency magnetic powders from the images observed using the above method, and the average value is taken as the "surface coverage of the iron oxide-containing region" of the high-frequency magnetic powder.

[0098] The iron oxide-containing region may include a highly electrically conductive metallic phase or intermetallic compound phase such as α-Fe, cementite (Fe3C), or Fe3B phase. In this case, if the metallic phase or intermetallic compound phase is present on the outermost surface, eddy currents will be generated throughout the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder having the iron oxide-containing region on its outer surface, worsening the efficiency of magnetic field amplification. Therefore, it is preferable that the metallic phase or intermetallic compound phase is not present on the outermost surface. To suppress the decrease in efficiency due to eddy currents, the thickness of the metallic phase or intermetallic compound phase is preferably 10 μm or less, more preferably 1 μm or less, and even more preferably 100 nm or less.

[0099] The iron oxide-containing region may also include, in addition to magnetite and / or maghemite, components derived from the core region, which is a rare-earth-iron-based high-frequency magnetic powder, or from the treatment agents (phosphorus-containing materials) and additives used during phosphorus treatment to form the phosphorus compound coating, such as Ni, Co, M components (at least one selected from the group consisting of Ti, V, Mo, Nb, W, Si, Al, Mn, and Cr), or Na, Mg, Ca, K, Cu, Pb, Zn, Zr, Mo, Ba, Hf, Ta, La, Y, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Lu, Sm, etc. Furthermore, the iron oxide-containing region may also include carbon, boron, etc., derived from the core region, which is a rare-earth-iron-based high-frequency magnetic powder, etc.

[0100] In addition, depending on the content of component M, substances that have the spinel structure of magnetite are called "M-ferrite," but in this disclosure, since the content of component M is small, less than 16.5 atomic percent, "M-ferrite" is also considered a substance that falls under the category of "magnetite." Furthermore, maghemite has the same crystalline structure as magnetite, a spinel structure, and its structure is such that 1 / 6 of the octahedral sites (octahedral sites) of the spinel-type crystalline structure are vacancies. The intermediate between magnetite and maghemite disclosed in N. Imaoka, E. Kakimoto, K. Takagi, K. Ozaki, M. Tada, T. Nakagawa, M. Abe, Journal of Magnetism and Magnetic Materials, vol. 476, pp. 613~621 (2019) also has a spinel-type crystalline structure, and in this disclosure, this intermediate is also considered a type of "magnetite."

[0101] <Method for producing phosphorus compound-coated rare earth-iron-based magnetic powder for high-frequency applications> The following describes an example of a method for producing the rare earth-iron-based high-frequency magnetic powder and the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder according to this embodiment. However, the method is not limited to the following, and other methods may also be used.

[0102] (Method for producing rare earth-iron-based magnetic powder for high-frequency applications) The method for producing the rare-earth-iron-based high-frequency magnetic powder constituting the core region is not particularly limited, but for example, the rare-earth-iron-based high-frequency magnetic powder can be produced by the solid-phase method or precipitation method shown below.

[0103] (Method for producing rare earth-iron-based magnetic powder for high-frequency applications: Solid-phase method) A method for producing rare earth-iron-based magnetic powder for high-frequency applications using a solid-phase method is as follows: A process of mixing rare earth oxide powder, Fe raw material, and Ca powder (mixing process), and The process of reducing the resulting mixture (reduction process), Includes. When manufacturing rare earth-iron-nitrogen-based magnetic powders for high-frequency applications, this method is used. A process of nitriding the alloy particles obtained in the reduction process (nitriding process). It also includes.

[0104] [Mixing process] In the mixing step, rare earth R oxide powder, Fe raw material, and Ca powder are mixed. Depending on the desired composition of the rare earth-iron-based high-frequency magnetic powder, other metal oxide powders or metal salts may also be added. As the Fe raw material, not only metallic Fe but also Fe2O3 and / or Fe3O4 can be used. When using Fe2O3 and / or Fe3O4, its content (total number of moles of Fe in Fe2O3 and / or Fe3O4 relative to the total number of moles of Fe in metallic Fe and Fe2O3 and / or Fe3O4) is preferably between 0.1 atomic% and 30 atomic%. Using these iron oxides (Fe2O3 and / or Fe3O4) can lead to a more uniform reaction overall in the subsequent reduction step, due to the heat of reaction when the iron oxide is reduced by Ca, potentially resulting in energy savings and improved yield. The amount of Ca powder mixed should be sufficient to reduce the rare earth R oxide and any other selectively mixed metal oxides. The amount of Ca powder to be mixed is preferably 0.5 to 3 times, and more preferably 1 to 2 times, relative to the equivalent amount of oxygen atoms contained in the rare earth R oxide, selectively mixed Fe2O3 and / or Fe3O4, and other metal oxides and metal salts.

[0105] [Reduction Process] In the reduction process, alloy particles are obtained by reducing the mixture (mixed powder) obtained in the mixing process. For example, the mixed powder obtained in the mixing process is placed in a heating container, the heating container is evacuated, and then heated while passing an inert gas such as argon gas through it, preferably at 600°C to 1300°C, more preferably at 700°C to 1200°C, and even more preferably at 800°C to 1100°C. If the heating temperature is below 600°C, the reduction reaction of the oxide may not proceed sufficiently. If the heating temperature exceeds 1300°C, the rare earth element R and Fe may melt and form lumps. Also, if the heating temperature is 700°C or higher, the reduction time can be shortened, and productivity tends to improve. If the heating temperature is 1200°C or lower, the scattering of Ca can be further reduced, and variability during reduction tends to be further reduced. From the viewpoint of shortening manufacturing time and reducing costs, the heat treatment time is preferably 4 hours or less, more preferably less than 120 minutes, and even more preferably less than 90 minutes. From the viewpoint of carrying out a more uniform reduction reaction, it is preferably 10 minutes or more, and more preferably 30 minutes or more. Here, as described above, if an appropriate amount of Fe2O3 and / or Fe3O4 is included in the mixed powder in addition to metallic Fe, the heat generated when iron oxide is reduced by Ca during heating can be used to efficiently carry out a uniform reduction reaction. On the other hand, as described above, if the amount of Fe2O3 and / or Fe3O4 mixed exceeds 30 atomic percent relative to the total amount of metallic Fe and Fe2O3 and / or Fe3O4 in terms of Fe element, extremely large heat generation may cause an explosion or scattering of powder. Furthermore, the particle size of the obtained rare earth-iron-based high-frequency magnetic powder can be controlled by controlling the heating temperature, i.e., the reduction temperature. Generally, the particle size of the powder tends to increase as the reduction temperature increases.

[0106] [Nitriding process] To obtain a rare-earth-iron-based magnetic powder for high-frequency applications containing nitrogen (N), i.e., a rare-earth-iron-nitrogen-based magnetic powder for high-frequency applications, the alloy particles obtained in the reduction process are subjected to a nitriding process (nitriding process). In the nitriding process, for example, the mixture is cooled in an inert gas such as argon gas to a temperature range of preferably 250°C to 800°C, more preferably 300°C to 600°C, and even more preferably 400°C to 550°C. After that, the heating container is evacuated again, and then nitrogen gas is introduced. The gas introduced is not limited to nitrogen, but may also be a gas containing nitrogen atoms, such as ammonia. Then, while passing nitrogen gas or a gas containing nitrogen atoms such as ammonia through the mixture at a pressure of atmospheric pressure or higher, the mixture is heated for several hours, preferably about 5 hours, preferably within the above temperature range, after which heating is stopped and the mixture is allowed to cool.

[0107] The product obtained after the reduction or nitriding process may contain, in addition to rare-earth-iron-based high-frequency magnetic powder or rare-earth-iron-nitrogen-based high-frequency magnetic powder, by-products such as calcium oxide (CaO) and unreacted metallic calcium (Ca), which may be present in a sintered mass. In this case, as a water washing step, the product can be placed in ion-exchanged water to separate the calcium oxide and other calcium-containing components from the high-frequency magnetic powder as calcium hydroxide suspensions. This water washing step may involve repeating stirring in water, standing, and removing the supernatant several times. Furthermore, the high-frequency magnetic powder may be washed with acetic acid or the like to thoroughly remove any remaining calcium hydroxide. Unreacted metallic calcium remaining after the reduction process usually becomes calcium nitride, which is easier to remove in the nitriding process. Therefore, it is preferable to perform the water washing step after the heat treatment in the nitriding process. Performing the water washing step after the nitriding process tends to result in a sharper particle size distribution in the obtained rare-earth-iron-based high-frequency magnetic powder.

[0108] (Method for producing rare earth-iron-based magnetic powder for high-frequency applications: Precipitation method) A method for producing rare earth-iron-based magnetic powder for high-frequency applications by precipitation is as follows: A step of mixing a solution containing rare earth elements R and Fe with a precipitating agent to obtain a precipitate containing R and Fe (precipitation step), A process of calcining the precipitate to obtain an oxide containing R and Fe (oxidation process), A step of obtaining a partial oxide by heat-treating an oxide in a reducing gas-containing atmosphere (pretreatment step), and A process for reducing partial oxides (reduction process), Includes. When manufacturing rare earth-iron-nitrogen-based magnetic powders for high-frequency applications, this method is used. A process of nitriding the alloy particles obtained in the reduction process (nitriding process). It also includes.

[0109] [Precipitation process] In the precipitation step, first, a raw material containing rare earth elements R and a raw material containing iron Fe are dissolved in a solvent, preferably a strongly acidic solution, to prepare a solution containing R and Fe. At this stage, other metal raw materials (compounds containing metals) are also added and dissolved, depending on the desired composition of the rare earth-iron-based high-frequency magnetic powder. The R and Fe raw materials are not limited as long as they can be dissolved in a strongly acidic solution (hereinafter also referred to as an acidic solution). For example, in terms of availability, oxides of R can be used as the R raw material, and iron sulfate (FeSO4) can be used as the Fe raw material. The concentration of the solution containing R and Fe can be appropriately adjusted within a range in which the R and Fe raw materials are substantially soluble in the acidic solution. In terms of solubility, sulfuric acid is a suitable acidic solution.

[0110] An insoluble precipitate containing R and Fe is obtained by reacting a solution containing R and Fe with a precipitating agent. The precipitate obtained is usually a particulate precipitate. Here, the solution containing R and Fe only needs to be a solution containing R and Fe when reacted with the precipitating agent. For example, the raw materials containing R and the raw materials containing Fe may be prepared as separate solutions, and each solution may be added dropwise to react with the precipitating agent. Even when preparing separate solutions, the solutions should be adjusted appropriately so that each raw material is substantially soluble in the acidic solution. The precipitating agent is not limited to alkaline solutions that react with a solution containing R and Fe to obtain a precipitate, and examples include aqueous ammonia and caustic soda, with caustic soda being preferred.

[0111] After separating the precipitate, it is preferable to desolvent the separated material to prevent the precipitate from redissolving in the remaining solvent during the subsequent oxidation heat treatment, which can lead to aggregation of the precipitate, changes in particle size distribution, powder particle size, etc., as the solvent evaporates. Specifically, a method for desolvation is to dry the material in an oven at 70°C to 200°C for 5 to 12 hours, for example, when water is used as the solvent.

[0112] The precipitation step may include a step of separating and washing the resulting precipitate. The washing step should be carried out as appropriate until the conductivity of the supernatant solution is 50 μS / cm or less. For example, to separate the precipitate, a solvent (preferably water) can be added to the obtained precipitate and mixed, followed by filtration, decantation, or the like.

[0113] [Oxidation process] In the oxidation process, an oxide containing R and Fe is obtained by calcining the precipitate formed in the precipitation process. For example, the precipitate can be converted to an oxide by heat treatment. When heat treating the precipitate, it is necessary to do so in the presence of oxygen, for example, in an atmospheric environment. Also, because it is necessary to do so in the presence of oxygen, it is preferable that the nonmetallic portion of the precipitate contains oxygen atoms. The heat treatment temperature in the oxidation process (hereinafter also referred to as the oxidation temperature) is not particularly limited, but is preferably 700°C to 1300°C, and more preferably 900°C to 1200°C. If the oxidation temperature is below 700°C, oxidation may be insufficient. If the oxidation temperature exceeds 1300°C, it tends to be difficult to obtain the desired shape, average particle size, and particle size distribution of the rare earth-iron-based high-frequency magnetic powder. The heat treatment time is also not particularly limited, but can be 0.5 hours to 4 hours, and preferably 1 hour to 3 hours.

[0114] [Pre-treatment process] In the pretreatment step, the oxide containing at least R and Fe obtained in the oxidation step is heat-treated in a reducing gas-containing atmosphere, such as hydrogen gas alone or a mixed gas containing hydrogen gas, preferably in a heating temperature range of 250°C to 850°C, for, for example, 15 minutes to 24 hours, to obtain a partial oxide in which a portion of the oxide has been reduced.

[0115] [Reduction Process] In the reduction step, the partial oxide obtained in the pretreatment step is reduced. For example, alloy particles are obtained by heating the partial oxide obtained in the pretreatment step in the presence of a reducing agent such as Ca, preferably at 600°C to 1300°C, more preferably at 700°C to 1200°C, and even more preferably at 800°C to 1100°C. If the heating temperature is below 600°C, the reduction reaction of the oxide may not proceed sufficiently. If the heating temperature exceeds 1300°C, the rare earth element R and Fe may melt and form lumps. Also, if the heating temperature is 700°C or higher, the reduction time can be shortened, and productivity tends to improve. If the heating temperature is 1200°C or lower, the scattering of the reducing agent Ca can be further reduced, and variability during reduction tends to be further reduced. By controlling this heating temperature, i.e., the reduction temperature, the particle size of the obtained rare earth-iron-based high-frequency magnetic powder can be controlled. In general, the particle size of the powder tends to increase as the reduction temperature increases. From the viewpoint of shortening manufacturing time and reducing costs, the heat treatment time is preferably less than 120 minutes, more preferably less than 90 minutes, and from the viewpoint of carrying out the reduction reaction more uniformly, it is preferably 10 minutes or more, more preferably 30 minutes or more.

[0116] [Nitriding process] When obtaining rare-earth-iron-based high-frequency magnetic powder containing nitrogen (N), i.e., rare-earth-iron-nitrogen-based high-frequency magnetic powder, the alloy particles obtained in the reduction step are subjected to nitriding (nitriding step). Since particulate precipitate obtained in the above-mentioned precipitation step is used, porous, lumpy alloy particles are obtained in the reduction step. As a result, nitriding can be performed immediately by heat treatment in a nitrogen atmosphere without the need for grinding, thus enabling uniform nitriding.

[0117] The heat treatment temperature (hereinafter also referred to as the nitriding temperature) in the nitriding treatment of alloy particles is preferably 250°C to 800°C, and more preferably 300°C to 600°C. Furthermore, although rare earth-iron-nitrogen-based high-frequency magnetic materials are basically nitride-based materials with excellent oxidation resistance and corrosion resistance, they are thermodynamically metastable compounds. Therefore, in order to suppress the decomposition of the nitride reactants in the latter half or final stage of the nitriding process and increase the reaction efficiency, it is particularly preferable that the nitriding temperature be 400°C to 550°C. The nitriding treatment is carried out within this temperature range by replacing the atmosphere with an atmosphere containing a nitrogen source such as nitrogen gas or ammonia gas. In other words, the nitriding treatment can be carried out by heat treatment within the above temperature range under an atmosphere containing a nitrogen source. The heat treatment time should be set to a length that ensures sufficiently uniform nitriding of the alloy particles.

[0118] In the precipitation method, as with the solid-phase method, it is preferable to perform a washing step or the like after the reduction step or nitriding step.

[0119] (Method for producing phosphorus-coated rare earth-iron-based magnetic powder for high-frequency applications) The method for producing rare earth-iron-based high-frequency magnetic powder (phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder) in which at least a portion of the surface is coated with a phosphorus compound is not particularly limited, but for example, phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, and furthermore, phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder having an α-Fe-containing region and an iron oxide-containing region, can be produced by the method shown below.

[0120] [Phosphorus treatment process: Formation process of phosphorus compound coated area] In the phosphorus treatment process, for example, an inorganic acid is added to a slurry containing rare earth-iron-based high-frequency magnetic powder, water, and a phosphorus-containing substance to coat at least a portion of the surface of the high-frequency magnetic powder with a phosphorus compound, that is, to form a phosphorus compound coating on at least a portion of the surface of the high-frequency magnetic powder, thereby obtaining phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder. The phosphorus compound coating of the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder is formed by the reaction of metal components (e.g., X components (Fe, Co, Ni) and rare earth elements R, etc.) contained in the rare earth-iron-based high-frequency magnetic powder with phosphorus components (e.g., phosphoric acid, etc.) contained in the phosphorus-containing substance, causing phosphorus compounds (e.g., phosphates such as iron phosphate, samarium phosphate, cerium phosphate, neodymium phosphate, etc.) to precipitate on the surface of the high-frequency magnetic powder.

[0121] In the phosphorus treatment process, using water as the solvent for the slurry allows for the precipitation of phosphorus compounds such as phosphates with smaller particle sizes compared to using an organic solvent. This results in rare-earth-iron-based high-frequency magnetic powders with a denser phosphorus compound coating, which tends to yield excellent efficiency in the high-frequency range (efficiency in magnetic field amplification characteristics) and excellent absorption characteristics in the ultra-high-frequency range.

[0122] The method for preparing a slurry containing rare earth-iron-based high-frequency magnetic powder, water, and a phosphorus-containing substance is not particularly limited, but can be obtained, for example, by mixing the rare earth-iron-based high-frequency magnetic powder with an aqueous solution of the phosphorus-containing substance. The content of the rare earth-iron-based high-frequency magnetic powder in the slurry is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 20% by mass or less from the viewpoint of productivity. The content of the phosphorus-containing substance in the slurry is not particularly limited, but if the phosphorus-containing substance is phosphoric acid and consists only of hydrogen and the phosphoric acid component (PO4), the content is preferably, for example, 0.01% by mass or more and 10% by mass or less in terms of PO4 equivalent, and more preferably 0.05% by mass or more and 5% by mass or less from the viewpoint of reactivity between the metal component and the phosphoric acid component and productivity.

[0123] Examples of phosphorus-containing materials include elemental phosphorus and compositions containing elemental phosphorus, phosphate compounds such as orthophosphoric acid, heteropoly acid compounds such as phosphotungstic acid and phosphomolybdic acid, salts of phosphorus-containing acid compounds such as phosphate compounds and heteropoly acid compounds with metal ions or ammonium ions, organophosphorus compounds such as phosphate esters, phosphite esters, and phosphine oxides, iron phosphide, phosphorus bronze, and phosphorus-containing metals such as Fe-BP-Cu and Fe-Nb-BP alloys.

[0124] When the phosphorus-containing substance is a phosphate compound (including salts), an aqueous solution of phosphoric acid is obtained by mixing the phosphate compound with water. Examples of phosphate compounds include phosphates such as orthophosphoric acid, sodium dihydrogen phosphate, sodium monohydrogen phosphate, ammonium dihydrogen phosphate, ammonium monohydrogen phosphate, zinc phosphate, and calcium phosphate; inorganic phosphates such as hypophosphorous acid, hypophosphite, pyrophosphoric acid, and polyphosphoric acid; and organic phosphates. These may be used individually or in combination of two or more. In addition, to improve the water resistance and corrosion resistance of the coating and the magnetic properties of the high-frequency magnetic powder, oxo salts such as molybdate, tungstate, vanadate, and chromate, oxidizing agents such as sodium nitrate and sodium nitrite, and chelating agents such as EDTA can be used as additives.

[0125] Among phosphorus-containing materials, inorganic phosphoric acids such as orthophosphoric acid, pyrophosphoric acid, and polyphosphoric acid, and phosphoric acid compounds such as phosphates of these with Na, Mg, Al, Ca, K, Ti, V, Cr, Mn, Ni, Cu, Pb, Zn, Fe, Zr, Mo, Ba, Hf, Ta, La, Y, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Lu, Sm, ammonium, etc. are preferred from the viewpoint of controlling the reaction and the amount of coating.

[0126] The concentration of phosphoric acid (in PO4 equivalent) in the aqueous phosphoric acid solution is preferably 5% to 50% by mass, and more preferably 10% to 30% by mass from the viewpoint of solubility of the phosphoric acid compound, storage stability, and ease of chemical treatment. The pH of the aqueous phosphoric acid solution is preferably 1 to 4.5, and more preferably 1.5 to 4 from the viewpoint of being able to easily control the precipitation rate of phosphates. The pH can be adjusted with dilute hydrochloric acid, dilute sulfuric acid, etc.

[0127] In the phosphorus treatment process, adjusting the pH of the slurry by adding an inorganic acid can increase the amount of phosphorus compound precipitated compared to when no inorganic acid is added. This results in phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder with a thick phosphorus compound coating (also called film thickness), which tends to improve tanδ and phase angle θ, and thus the magnetic field amplification characteristics. The pH of the slurry is preferably adjusted to between 1 and 4.5, more preferably between 1.6 and 3.9, and even more preferably between 2 and 3. If the pH is less than 1, the rare-earth-iron-based high-frequency magnetic powders may aggregate, starting from locally precipitated phosphorus compounds, which can worsen tanδ and phase angle θ in the high-frequency range. If the pH exceeds 4.5, the amount of phosphorus compounds such as phosphates precipitated decreases, resulting in insufficient coating by phosphorus compounds, which can also worsen tanδ and phase angle θ in the high-frequency range. Examples of inorganic acids to be added include hydrochloric acid, nitric acid, sulfuric acid, boric acid, and hydrofluoric acid. During the phosphorus treatment process, it is preferable to add inorganic acids as needed to maintain the pH within the above range. Inorganic acids are used from the standpoint of wastewater treatment, but organic acids can also be used in combination depending on the purpose. Examples of organic acids include acetic acid, formic acid, and tartaric acid.

[0128] The adjustment of the pH of the slurry containing rare earth-iron-based high-frequency magnetic powder, water, and phosphorus-containing material to a range of 1 to 4.5 is preferably carried out for 10 minutes or more, and more preferably for 30 minutes or more, in order to reduce the area where the coating is thin. In the initial stages of pH maintenance, the pH rises rapidly, so the interval between adding the inorganic acid for pH control is short, but as the coating progresses, the pH fluctuations gradually slow down, and the interval between adding the inorganic acid lengthens, allowing the reaction endpoint to be determined.

[0129] [Oxidation process after phosphorus treatment: Formation process of α-Fe-containing region] In the oxidation step after phosphorus treatment, the rare-earth-iron-based high-frequency magnetic powder having a phosphorus compound coating obtained in the phosphorus treatment step (phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder) is heat-treated in an oxygen-containing atmosphere, preferably at 350°C to 600°C, to form an α-Fe-containing region between the rare-earth-iron-based high-frequency magnetic powder (core region) and the phosphorus compound coating. Here, it is thought that the heat treatment (oxidation treatment) in an oxygen-containing atmosphere causes oxidation of the surface of the rare-earth-iron-based high-frequency magnetic powder from the interface between the phosphorus compound coating and the rare-earth-iron-based high-frequency magnetic powder, forming an α-Fe-containing region disproportionately composed of an α-Fe phase and a phase selected from the group consisting of oxides, nitrides, and oxynitrides containing rare earth R. By performing an oxidation step after the phosphorus treatment step, it is thought that excessive thermal decomposition of the rare-earth-iron-based high-frequency magnetic powder (core region) can be avoided, while gradually separating and dispersing the α-Fe phase from the matrix (the homogeneous rare-earth-iron-based high-frequency magnetic material crystalline phase with spatial symmetry at the atomic level before disproportionation) at the nanoscale through a disproportionation reaction from the surface of the rare-earth-iron-based high-frequency magnetic powder beneath the phosphorus compound coating. Note that this step does not need to be performed if an α-Fe-containing region is not to be formed.

[0130] As described above, the oxidation treatment is carried out by heat-treating phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder in an oxygen-containing atmosphere. The reaction atmosphere is preferably a mixed gas atmosphere of oxygen and an inert gas, such as nitrogen or argon containing oxygen. The oxygen concentration in the mixed gas is preferably 3% to 25% by volume, and more preferably 3.5% to 21% by volume. Depending on the reaction temperature and reaction time, the oxygen concentration in the mixed gas may be 25% by volume or higher. During the oxidation reaction, it is preferable to exchange the gas at a flow rate of 2 L / min to 10 L / min per 1 kg of high-frequency magnetic powder.

[0131] The heat treatment temperature during oxidation (hereinafter also referred to as the oxidation treatment temperature) varies depending on the composition of the rare-earth-iron-based high-frequency magnetic powder (core region) and the surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder (core region) by phosphorus compounds, but is preferably 300°C to 600°C, more preferably 320°C to 550°C, even more preferably 330°C to 500°C, and still more preferably 350°C to 480°C. If the oxidation treatment temperature is below 300°C, the real term μ' of the complex relative permeability in the high-frequency region may decrease. If the oxidation treatment temperature exceeds 600°C, the rare-earth-iron-based high-frequency magnetic powder tends to decompose excessively. The heat treatment time (oxidation treatment time) can be, for example, 30 minutes or more, 1 hour or more, or 3 hours or more. The heat treatment time (oxidation treatment time) can be 20 hours or less, or 10 hours or less.

[0132] [Annealing process: process for forming iron oxide-containing regions] In the annealing process, the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder having an α-Fe-containing region, obtained in the oxidation process after phosphorus treatment (hereinafter also referred to as α-Fe-containing phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder), is heat-treated in an atmosphere consisting of an inert gas and / or a reducing gas that does not contain nitrogen atoms, preferably at a temperature of 200°C to 600°C, thereby forming an iron oxide-containing region on (outside) the phosphorus compound coating. Here, in the oxidation process after phosphorus treatment, an iron oxide layer (hematite layer) mainly composed of hematite may precipitate on (outside) the phosphorus compound coating. It is thought that by heat treatment (annealing) in an atmosphere consisting of an inert gas and / or a reducing gas that does not contain nitrogen atoms, at least a portion of the hematite in the iron oxide layer formed on (outside) the phosphorus compound coating is reduced or transformed into magnetite or maghemite, and an iron oxide-containing region containing magnetite and / or maghemite is formed. Note that if an iron oxide-containing region is not formed, this process does not need to be performed.

[0133] As described above, the annealing treatment is performed by heat-treating the α-Fe-containing phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder in an atmosphere consisting of an inert gas and / or a reducing gas that does not contain nitrogen atoms. Examples of inert gases include Ar gas, N2 gas, Ne gas, and He gas. Examples of reducing gases that do not contain nitrogen atoms include H2 gas and CO gas. A mixture of these gases may also be used. The oxygen concentration in the atmosphere during the annealing treatment is preferably 0.1% by volume or less, and more preferably 0.01% by volume or less.

[0134] The heat treatment temperature during annealing (hereinafter also referred to as the annealing temperature) varies depending on the composition of the rare-earth-iron-based high-frequency magnetic powder (core region) and the surface coverage rate of the rare-earth-iron-based high-frequency magnetic powder (core region) by the phosphorus compound, but is preferably 200°C to 600°C, more preferably 350°C to 600°C, even more preferably 380°C to 550°C, and still more preferably 400°C to 480°C. If the annealing temperature is below 200°C, the treatment time tends to be very long. If the annealing temperature exceeds 600°C, the phosphorus compound coating (film made of phosphorus compound) tends to deteriorate easily. The heat treatment time (annealing time) can be, for example, 10 minutes or more, 1 hour or more, or 3 hours or more. The heat treatment time (annealing time) can be 20 hours or less, or 6 hours or less.

[0135] The α-Fe-containing phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder may undergo an annealing step, in which it is heat-treated in an atmosphere consisting of an inert gas and / or a reducing gas that does not contain nitrogen atoms, preferably at 200°C to 600°C. This annealing step may then be followed by a heat-treatment step in an oxygen-containing atmosphere, preferably at 200°C to 600°C. This heat treatment step in an oxygen-containing atmosphere can also oxidize the magnetite contained in the iron oxide-containing region to maghemite. The oxygen-containing atmosphere is preferably an atmosphere containing oxygen in an inert gas such as nitrogen or argon, i.e., a mixed gas atmosphere of oxygen and an inert gas. The oxygen-containing atmosphere may also contain water vapor, and the heat treatment can be performed in a water vapor-containing atmosphere (for example, a mixed gas atmosphere of water vapor and an inert gas) instead of oxygen. In this embodiment, the oxygen-containing atmosphere means one that contains an oxygen source, and since a water vapor-containing atmosphere contains an oxygen source, it is a type of oxygen-containing atmosphere. The oxygen concentration in the mixed gas is preferably 3% to 25% by volume, and more preferably 3.5% to 21% by volume. The heat treatment temperature is preferably 200°C to 600°C, more preferably 200°C to 500°C, and even more preferably 200°C to 300°C.

[0136] [Silica treatment process] Rare earth-iron-based high-frequency magnetic powder having a phosphorus compound coating obtained in the phosphorus treatment process (phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder) may be subjected to an oxidation process and an annealing process after phosphorus treatment as needed, and further silica treatment as needed. By forming a silica thin film on the high-frequency magnetic powder, oxidation resistance can be improved. The silica thin film can be formed, for example, by mixing alkyl silicate, phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder (which may be phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder having an α-Fe-containing region and / or an iron oxide-containing region), and an alkaline solution.

[0137] [Silane coupling treatment process] After the phosphorus treatment process, the obtained high-frequency magnetic powder may be further treated with a silane coupling agent after performing oxidation, annealing, silica treatment, etc., as necessary. By performing silane coupling treatment on the magnetic powder on which a silica thin film has been formed, a silane coupling agent film is formed on the silica thin film, which improves the magnetic properties of the high-frequency magnetic powder and can also improve the wettability with resin and the strength of the molded article.

[0138] The silane coupling agent can be selected according to the type of resin and is not particularly limited, but examples include γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. Lan, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethylenedisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyl[3-(trimethoxysilyl)propyl]ammonium chloride, γ-chloropropylmethyldimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, Vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, oleidopropyltriethoxysilane, γ-isocyanatetopropyltriethoxysilane, Examples of silane coupling agents include polyethoxydimethylsiloxane, polyethoxymethylsiloxane, bis(trimethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)tetrasulfan, γ-isocyanatetopropyltrimethoxysilane, vinylmethyldimethoxysilane, 1,3,5-N-tris(3-trimethoxysilylpropyl)isocyanurate, t-butylcarbamatetrialkoxysilane, and N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine. These silane coupling agents may be used individually or in combination of two or more.The amount of silane coupling agent added is preferably 0.2 parts by mass or more and 0.8 parts by mass or less, and more preferably 0.25 parts by mass or more and 0.6 parts by mass or less, per 100 parts by mass of high-frequency magnetic powder. If the amount of silane coupling agent added is less than 0.2 parts by mass, the effect of the silane coupling agent will be reduced. If the amount of silane coupling agent added exceeds 0.8 parts by mass, aggregation of the high-frequency magnetic powder may occur, which may reduce the magnetic properties of the high-frequency magnetic powder and the molded body.

[0139] Furthermore, the silica treatment process and / or the silane coupling treatment process may be omitted, or after these treatment processes, isopropyl triisostearoyl titanate, isopropyl tri(N-aminoethyl-aminoethyl) titanate, isopropyl tris(dioctyl pyrophosphate) titanate, tetraisopropyl bis(dioctyl phosphite) titanate, tetraisopropyl titanate, tetrabutyl titanate, tetraoctyl bis(ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, and isopropyl tridodecylbenzenesulfonate may be added. High-frequency magnetic powders can be surface-treated using titanium-based coupling agents such as yl titanate, isopropyl tri(dioctyl phosphate) titanate, bis(dioctyl pyrophosphate)ethylene titanate, isopropyl dimethacrylate isostearoyl titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis(ditridecyl phosphite) titanate, and isopropyl tricumylphenyl titanate, as well as aluminum-based, zirconium-based, chromium-based, iron-based, and tin-based coupling agents such as acetalkoxyaluminum diisopropylate. When bonded magnetic materials are made using high-frequency magnetic powders treated with coupling agents (including the silane coupling treatment described above), the affinity with the added resin is improved, the phosphorus compound-coated rare earth-iron high-frequency magnetic powders become more easily isolated and dispersed, the electrical insulation between high-frequency magnetic powders is further improved, and superior efficiency (efficiency in magnetic field amplification characteristics) may be exhibited in the high-frequency range, and superior absorption characteristics may be exhibited in the ultra-high-frequency range.

[0140] High-frequency magnetic powders after a phosphorus treatment process, an oxidation process following phosphorus treatment, an annealing process, a silica treatment process, or a silane coupling treatment process can be filtered, dehydrated, and dried by conventional methods.

[0141] The phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder may have its particle size distribution homogenized in order to improve the real term μ' of the complex relative permeability in the high-frequency range and the imaginary term μ'' of the complex relative permeability in the ultra-high-frequency range. This homogenization of particle size distribution can be performed by general dry classification or wet classification methods. The homogenization of particle size distribution may be performed before the phosphorus treatment, after the phosphorus treatment, after the oxidation process following phosphorus treatment, after the annealing process, after the silica treatment process, or after the silane coupling treatment process.

[0142] <Magnetic metals and / or metal oxides> The magnetic material composition for magnetic field amplification of this embodiment includes a phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, in addition to a magnetic metal and / or metal oxide. Here, the magnetic metal may be an alloy, and the magnetic metal oxide may be a composite oxide. The magnetic metal and / or metal oxide are usually included in the magnetic material composition for magnetic field amplification in the form of powder or particles.

[0143] By introducing magnetic metals and / or metal oxides into the voids between phosphorus compound-coated rare-earth-iron high-frequency magnetic powders, while maintaining electrical insulation between the core region of the phosphorus compound-coated rare-earth-iron high-frequency magnetic powder and the magnetic metals and / or metal oxides, the demagnetizing field of the high-frequency magnetic material powder decreases, and the real term μ' of the complex relative permeability increases. The presence of magnetic metals and / or metal oxides increases the volume fraction of the magnetic component, thereby improving relative permeability. However, the rate of improvement (rate of increase in relative permeability) does not increase directly in proportion to the volume fraction of the magnetic component, but rather increases hyperbolically. This is thought to be due to the decrease in the demagnetizing field. As the volume fraction of the magnetic component, including magnetic metals and / or metal oxides, increases, that is, as it approaches 1, the rate at which relative permeability improves due to this demagnetizing field tends to increase rapidly.

[0144] Examples of magnetic metals include Fe (preferably carbonyl iron), Ni, Co, Fe-Ni alloys, Fe-Ni-Si alloys, Sendust, Fe-Si-Al alloys, Fe-Si-Cr alloys, Fe-Cu-Nb-Si alloys, amorphous alloys, etc. Examples of magnetic metal oxides include spinel-type ferrites such as maghemite, magnetite, Ni-ferrite, Zn-ferrite, Mn-Zn ferrite, Ni-Zn ferrite, and Ni-Mn ferrite, as well as garnet-type ferrites and magnetoplanbite-type ferrites. In terms of further improving the magnetic field amplification characteristics of the magnetic material composition, it is preferable that the magnetic metal and / or metal oxide added to the magnetic material composition for magnetic field amplification be one or more of Ni, Fe (preferably carbonyl iron), or magnetite (Fe3O4).

[0145] When applied to magnetic material compositions for magnetic field amplification, the average particle size of the magnetic metal and / or metal oxide is not particularly limited, but is preferably 1 nm to 100 μm, more preferably 2 nm to 50 μm, and even more preferably 3 nm to 20 μm. If the average particle size of the magnetic metal and / or metal oxide exceeds 100 μm, losses in the high-frequency range due to eddy current losses increase, which can degrade the magnetic field amplification characteristics. If the average particle size of the magnetic metal and / or metal oxide is less than 1 nm, moldability deteriorates, aggregation of the metal and / or metal oxide becomes more likely, and the affinity and effect of small-particle metal and / or metal oxide powders on rare-earth-iron-based high-frequency magnetic powders, such as improving the dispersibility of the rare-earth-iron-based high-frequency magnetic powder, may not be fully utilized. Here, an average particle size of 0.1 μm or more refers to the median diameter measured under dry conditions using a laser diffraction particle size distribution analyzer. An average particle size of less than 0.1 μm refers to the median diameter measured under wet conditions using a dynamic light scattering particle size distribution analyzer. Alternatively, in the case of magnetic material compositions (compounds, molded articles, etc.), a method can be used in which the particle size of 20 or more, preferably 50 or more, powder particles representing the entire material sufficiently from a microscopic image such as a TEM, STEM, or SEM is measured to determine the volume particle size distribution, and then the median diameter is obtained. In the above, the average particle size can be expressed as D50, where D50 is the particle size corresponding to 50% of the cumulative value of the volume-based particle size distribution of the magnetic metal and / or metal oxide powder.

[0146] The shape of the magnetic metal and / or metal oxide is not particularly limited and may be any shape, such as spherical, plate-like, flattened, flaky, needle-like, fibrous, or irregularly shaped. However, a spherical shape is generally preferred in order to ensure that the magnetic metal is homogeneously present at the grain boundaries of the rare-earth-iron-based high-frequency magnetic powder and is magnetically isotropic.

[0147] It is desirable that magnetic metals and / or metal oxides be as close together as possible, even if a thin insulating layer is present on their surface. In this case, the demagnetizing field becomes lower, and the real term μ' of the complex relative permeability can be increased. Therefore, the ratio of the amount of magnetic metals and / or metal oxides to the total amount of other non-magnetic components is preferably 10 volume% or more. To achieve a higher real term μ' of the complex relative permeability, it is more preferably 25 volume% or more, even more preferably 50 volume% or more, and may even be 100 volume%.

[0148] In the magnetic material composition for magnetic field amplification, the content (total content) of magnetic metals and / or metal oxides is preferably 0.1 parts by mass or more and 100 parts by mass or less, more preferably 0.2 parts by mass or more and 50 parts by mass or less, and even more preferably 0.5 parts by mass or more and 25 parts by mass or less, per 100 parts by mass of the rare earth-iron-based high-frequency magnetic powder (the entire rare earth-iron-based high-frequency magnetic powder, including the core region, the phosphorus compound coating region, and the iron oxide-containing region on the surface). When the content of magnetic metals and / or metal oxides is 0.1 parts by mass or more per 100 parts by mass of the rare earth-iron-based high-frequency magnetic powder, the addition of magnetic metals and / or metal oxides can improve the packing density of magnetic components per unit volume and reduce the demagnetizing field, and as a result, a sufficient effect of increasing the real term μ' of the complex relative permeability can be obtained. Furthermore, if the content of magnetic metals and / or metal oxides is 100 parts by mass or less per 100 parts by mass of rare earth-iron-based high-frequency magnetic powder, the content of rare earth-iron-based high-frequency magnetic powder in the composition is sufficiently ensured, resulting in a composition with superior magnetic field amplification characteristics, particularly excellent efficiency. This makes it suitable for use in applications requiring both high efficiency and high permeability, such as transformers and inductors used in the high-frequency range.

[0149] <Resin> The magnetic material composition for magnetic field amplification in this embodiment may further include a resin in addition to a phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder and a magnetic metal and / or metal oxide. Such a composite material of magnetic material and resin is sometimes called a "bonded magnetic material composition."

[0150] Molded articles that do not contain a resin that functions as a binder, such as compacted powders using auxiliary agents such as volatile organic solvents, are very brittle and are generally difficult to apply to applications such as magnetic cores of wireless power transmission coils and inductors that are subjected to loads. Furthermore, for example, pressure-molded compacted powders contain many air layers that penetrate the molded article, and tend to oxidize or become brittle and lose impact resistance when exposed to temperatures of 50°C or higher for extended periods, and are generally unsuitable for high-temperature applications. Therefore, it is preferable that molded articles (magnetic material compositions for magnetic field amplification) applied to the above-mentioned applications further contain a resin in addition to phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder and magnetic metals and / or metal oxides.

[0151] The resin included in the bonded magnetic material composition is not particularly limited and may be either a thermoplastic resin or a thermosetting resin. Examples of thermoplastic resins include polyphenylene sulfide (PPS), polyether ether ketone (PEEK), liquid crystal polymer (LCP), polyamide (PA), polypropylene (PP), polyethylene (PE), and thermoplastic elastomers. Examples of thermosetting resins include epoxy resins, phenolic resins, urea resins, melamine resins, guanamine resins, unsaturated polyester resins, vinyl ester resins, diallyl phthalate resins, polyurethane resins, silicone resins, polyimide resins, alkyd resins, furan resins, dicyclopentadiene resins, acrylic resins, allyl carbonate resins, and thermosetting elastomers generally referred to as rubber.

[0152] The resin content in a bonded magnetic material composition (magnetic material composition for magnetic field amplification) is generally preferably 0.1% to 95% by mass, depending on the application, and more preferably 0.5% to 50% by mass depending on the application. When the resin content is 0.1% by mass or more, more preferably 0.5% by mass or more, the impact resistance, dielectric strength, dielectric breakdown resistance, and magnetic saturation resistance (resistance to magnetic saturation) of the bonded magnetic material composition tend to improve. When the resin content is 95% by mass or less, more preferably 50% by mass or less, extreme decreases in relative permeability (real term μ' of complex relative permeability) and magnetization can be suppressed, and desired high-frequency characteristics (magnetic field amplification characteristics in the high-frequency range) and high relative permeability can be ensured. Furthermore, for example, when used as a transformer for high-frequency circuits with particularly excellent efficiency, it is especially preferable for the resin content to be 1% to 15% by mass. Furthermore, in order to obtain a particularly high real term μ' of the complex relative permeability and particularly excellent magnetic field amplification characteristics as a magnetic material composition for magnetic field amplification, the resin content in the bonded magnetic material composition (magnetic material composition for magnetic field amplification) is generally 15% by mass or less, although this may vary slightly depending on the application.

[0153] <Other ingredients / additives> The magnetic material composition for magnetic field amplification of this embodiment may further contain other components and additives as needed, as long as they do not impair the effects of this embodiment. Examples of other components and additives include lubricants, heat-resistant anti-aging agents / heat-resistant stabilizers, antioxidants, fillers, ultraviolet absorbers, antistatic agents, colorants, and fillers. These may be used individually or in combination of two or more.

[0154] Examples of lubricants include waxes such as paraffin wax, liquid paraffin, polyethylene wax, polypropylene wax, ester wax, carnauba wax, and microwax; fatty acids such as stearic acid, 12-oxystearic acid, and lauric acid; fatty acid salts such as zinc stearate, calcium stearate, barium stearate, aluminum stearate, magnesium stearate, zinc laurate, calcium laurate, zinc ricinoleate, calcium ricinoleate, and zinc 2-ethylhexoate; fatty acid amides such as stearamide, hydroxystearate, and palmitamide; fatty acid esters such as butyl stearate; alcohols such as ethylene glycol and stearyl alcohol; polysiloxanes such as silicone oil, silicone grease, silicone resin, and polysilane coupling agents; and inorganic compound powders such as Si3N4, SiC, MgO, Al2O3, TiC, and Sb2O3. Lubricants may be used individually or in combination of two or more types. As a lubricant, at least one of waxes, polysiloxanes, or fatty acid salts is preferred from the viewpoint of improving moldability. The lubricant content in the magnetic material composition for magnetic field amplification is usually preferably 5% by mass or less. If the lubricant content exceeds 5% by mass, the plasticizing effect increases, which may result in a decrease in the mechanical strength of the resulting molded article, bleed-out, or a decrease in the real term μ' of the complex relative permeability. In the magnetic material composition for magnetic field amplification of this embodiment, a lubricant is not necessarily required, but for example, if the total content of rare earth-iron-based high-frequency magnetic powder and magnetic metals and / or metal oxides increases and the moldability of the composition decreases, it may be preferable to add a lubricant.

[0155] Examples of heat-resistant anti-aging agents, heat-resistant stabilizers, or antioxidants include various hindered phenols such as N,N'-hexamethylene-bis(3,5-di-tert-butyl-hydroxycinnamamide), 4,4'-bis(2,6-di-tert-butylphenol), and 2,2'-methylenebis(4-ethyl-6-tert-butylphenol); aromatic amines such as N,N'-bis(β-naphthyl)-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, and poly(2,2,4-trimethyl-1,2-dihydroquinoline); copper salts such as copper chloride and copper iodide; sulfur compounds such as dilaurylthiodipropionate; and phosphorus compounds. Heat-resistant anti-aging agents, heat-resistant stabilizers, and antioxidants can be added, for example, to improve the heat resistance of magnetic material compositions for magnetic field amplification.

[0156] Examples of fillers include inorganic fillers made from oxides such as silica, alumina, titania, and mica; nitrides such as boron nitride and titanium nitride; graphite, glass, potassium titanate, barium sulfate, and nonmagnetic metals such as Cu; and organic fillers made from organic materials such as Teflon (registered trademark). The shape of the filler is not particularly limited and can be spherical or whisker-shaped, for example.

[0157] In the magnetic material composition for magnetic field amplification of this embodiment, the other components and additives described above may be added at any of the stages of mixing, kneading, or molding of the magnetic material composition for magnetic field amplification, or they may be added to the resin component in advance.

[0158] The content of these other components and additives in the magnetic material composition for magnetic field amplification is usually preferably 50% by mass or less, more preferably 25% by mass or less, and even more preferably 10% by mass or less. If the content of these other components and additives exceeds 50% by mass, the relative permeability decreases, which is undesirable except in applications where high dielectric strength, dielectric breakdown resistance, and magnetic saturation resistance are required.

[0159] <Applications of magnetic material compositions for magnetic field amplification> The magnetic material composition for magnetic field amplification of this embodiment can typically be suitably used at frequencies of 1 MHz or more and less than 1 GHz. In the low frequency band below 1 MHz, where even high-permeability metallic materials with low electrical resistance can be used, the characteristics of the material of this embodiment, such as high electrical resistivity and excellent magnetic field amplification characteristics in the high-frequency range even with large particle sizes, cannot be fully utilized. On the other hand, in the frequency band above 1 GHz, the imaginary term μ'' of the complex relative permeability of the material of this embodiment becomes large, and depending on the application, the efficiency may not be sufficient, and in many cases, it becomes preferable to use it as a magnetic material for ultra-high frequency absorption. When used as a magnetic material composition for magnetic field amplification at frequencies within the above range, rare-earth-iron-based high-frequency magnetic powder with an average particle size of 3 μm or more and 100 μm or less can be suitably used. In this case, there is no need to use fine grinding equipment such as a jet mill, and magnetic field orientation can be performed with a relatively low magnetic field, eliminating the need for magnetic field orientation with a high magnetic field that reduces throughput, which is preferable in terms of balancing cost and characteristics.

[0160] Specific applications of the magnetic material composition for magnetic field amplification of this embodiment are not particularly limited, but include magnetic materials for magnetic field amplification used in coils, antennas, and couplers for wireless power transmission operating at frequencies of 6 MHz or more and less than 1 GHz, magnetic materials for magnetic field amplification for RFID (Radio Frequency Identification) tags operating at frequencies of 10 MHz or more and less than 1 GHz, particularly using high frequencies of 920 MHz, and transformers, inductors, and reactors for high-frequency circuits exceeding 20 MHz. The magnetic material composition for magnetic field amplification for these applications preferably contains a resin that functions as a binder and has a product form such as a sheet, cylindrical or rectangular parallelepiped. Herein, the magnetic material for magnetic field amplification that can be used at frequencies of 1 MHz or more and less than 1 GHz in this embodiment, for example, the magnetic material for magnetic field amplification used in coils, antennas, and couplers for wireless power transmission operating at frequencies of 6 MHz or more and less than 1 GHz, can, depending on its usage, have a magnetic field amplification function at frequencies of 1 MHz or more and less than 1 GHz, or at frequencies of 6 MHz or more and less than 1 GHz, while simultaneously possessing a high-frequency shielding function that has an effect equivalent to a high-frequency absorption function of 30 MHz or more and less than 1 GHz, and can even have an ultra-high-frequency absorption function up to 1 GHz or less.

[0161] Specific applications of the magnetic material composition for magnetic field amplification according to this embodiment include magnetic materials for magnetic field amplification for flat coils on electronic circuit boards operating at frequencies of 50 MHz or more and less than 1 GHz. For this application, the magnetic material composition for magnetic field amplification may exist in the form of an ink or paste containing an organic solvent or an aqueous solvent. The ink or paste-like magnetic material composition for magnetic field amplification may also contain a resin that functions as a binder after drying or curing. Examples of resins that function as a binder after curing include thermosetting resins and UV-curable resins, and in some cases, this resin may also serve as the organic solvent for forming the ink or paste. The resin used is not particularly limited and can be appropriately selected according to the desired application and usage of the ink or paste.

[0162] The magnetic material composition for magnetic field amplification of this embodiment can be used as a magnetic material for magnetic field amplification by, for example, attaching it to the back surface of an antenna or transmitter / receiver and concentrating the magnetic flux within the sheet due to its magnetic field amplification characteristics; inserting it into a coil in the shape of a cylinder or rectangular parallelepiped; or shaping it into a donut shape or a magnetic core with a yoke and winding a wire around it to improve the real term μ' of the complex relative permeability of the coil. Furthermore, the magnetic material composition for magnetic field amplification of this embodiment can also be applied to the surface or interior of electronic circuits as a magnetic ink for forming magnetic paths of magnetic flux generated by planar coils, etc., or as a magnetic ink for forming various magnetic circuits.

[0163] The magnetic material composition for magnetic field amplification in this embodiment typically exhibits small frequency dependence of relative permeability (the real term μ' and imaginary term μ") of the complex relative permeability. Here, materials in which μ' changes significantly in a specific frequency range tend to show a corresponding large deviation of μ'' from 0, resulting in deterioration of tanδ and phase angle θ, and a decrease in efficiency. For example, in wireless power transmission applications using a frequency of 13.56 MHz, a magnetic material composition in which the real term μ' of the complex relative permeability changes little in the range of 2 MHz to 20 MHz, including that frequency, tends to have excellent efficiency and can be suitably used. In other applications as well, a magnetic material composition in which the real term μ' of the complex relative permeability is stable (changes little) in the frequency range corresponding to the application can be suitably used.

[0164] <Method for manufacturing magnetic material compositions and bonded magnetic material compositions for magnetic field amplification> The following describes an example of a method for manufacturing a magnetic material composition for magnetic field amplification according to this embodiment, particularly a bonded magnetic material composition (molded body) containing resin. However, the method is not limited to the following, and it can also be manufactured by other methods.

[0165] The compound for the bonded magnetic material composition according to this embodiment can be obtained, for example, by mixing and / or kneading phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, and a resin using a kneader. The mixing and kneading method and conditions are not particularly limited and can be appropriately selected by referring to known methods. The kneading temperature can be appropriately selected according to the type of resin used, etc., and is preferably, for example, above room temperature and below 150°C.

[0166] For example, a compound for bonded magnetic material compositions can be obtained by mixing phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, and a thermosetting resin using a roll or the like, and then grinding the mixture with a pulverizer.

[0167] A molded body of the bonded magnetic material composition can be produced by molding the obtained compound for bonded magnetic material composition using a suitable molding machine. Specifically, for example, a green body is produced by filling the mold of a compression molding machine with the compound and pressing it. During this compression molding, a uniaxial magnetic field or a rotating magnetic field may be applied to the compound to align the easy magnetization axis, easy magnetization plane, or hard magnetization axis of the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder in the green body (magnetic field orientation). When magnetic field orientation is applied, the real term μ' of the complex relative permeability tends to increase, and the resonance frequency tends to shift to a lower side. The green body can be transferred to a heat treatment furnace and cured by heating, preferably in a vacuum, to produce a molded body. The molding temperature can be appropriately selected according to the type of resin used, and other molding conditions (including the conditions of the magnetic field orientation process) are not particularly limited and can be appropriately selected.

[0168] Furthermore, when a thermoplastic resin is used, for example, a compound for bonded magnetic material compositions can be produced by mixing a phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, and a thermoplastic resin in a mixer and kneading them in an extruder. The resulting compound can then be injection molded to produce a molded body of the bonded magnetic material composition, or a sheet of the bonded magnetic material composition can be produced by press working or calendering. In this case as well, a magnetic field can be applied during injection molding, press working, or calendering to cause magnetic field orientation. The molding temperature and processing temperature can be appropriately selected according to the type of resin used, and other molding and processing conditions (including the conditions for the magnetic field orientation process) are not particularly limited and can be appropriately selected.

[0169] Furthermore, the molding method is not limited to compression molding, injection molding, press working, or calendering; bonded magnetic material compositions (molded bodies) can also be manufactured by transfer molding, extrusion molding, etc. Additionally, resin-free magnetic material compositions for magnetic field amplification can be obtained as molded bodies by, for example, sintering. The molding conditions in this case are not particularly limited and can be selected as appropriate.

[0170] Furthermore, the magnetic material composition for magnetic field amplification according to this embodiment can be in the form of an ink or paste, as described above. An ink or paste-like magnetic material composition for magnetic field amplification can be obtained, for example, by mixing a phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, an organic solvent and / or an aqueous solvent, and a resin that functions as a binder after drying or curing. The mixing method and conditions are not particularly limited and can be appropriately selected by referring to known methods. The content of the solvent (organic solvent and / or aqueous solvent) and resin in the magnetic material composition for magnetic field amplification is not particularly limited and can be appropriately selected according to the desired application and usage of the ink or paste. In some cases, an ink or paste-like magnetic material composition for magnetic field amplification can also be prepared without adding an organic solvent.

[0171] An ink or paste-like magnetic material composition for magnetic field amplification can be dried after application, or, if it contains a curable resin, the resin can be cured to form a film or layer of the magnetic material composition for magnetic field amplification. In this case as well, a magnetic field can be applied during drying or curing to cause magnetic field orientation. The application method and conditions are not particularly limited and can be appropriately selected by referring to known methods. Similarly, the drying method and conditions, as well as the curing method and conditions, are not particularly limited and can be appropriately selected by referring to known methods, depending on the type of organic solvent and resin used.

[0172] <<Magnetic material composition for ultra-high frequency absorption>> A magnetic material composition for ultra-high frequency absorption according to one embodiment of the present invention comprises a rare-earth-iron-based high-frequency magnetic powder (phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder) containing rare earth elements R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, with at least a portion of its surface coated with a phosphorus compound, and a magnetic metal and / or metal oxide. By adding a magnetic metal and / or metal oxide to a magnetic material composition for ultra-high frequency absorption containing a phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder, the imaginary term μ'' of the complex relative permeability and / or the imaginary term ε'' of the complex relative permittivity increase, particularly in the ultra-high frequency region (1 GHz to 1 THz), thereby improving the electromagnetic wave absorption characteristics, i.e., ultra-high frequency absorption characteristics, in this region.

[0173] In this embodiment, the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder may be used alone or in combination of two or more types. The magnetic metal and / or metal oxide may also be used alone or in combination of two or more types. Furthermore, one or more magnetic metals may be used without using magnetic metal oxides, one or more magnetic metal oxides may be used without using magnetic metals, and one or more magnetic metals and one or more magnetic metal oxides may be used in combination.

[0174] In one embodiment of this model, the ultra-high frequency absorbing magnetic material composition may further contain a resin. The resin may be used alone or in combination of two or more types. Furthermore, the ultra-high frequency absorbing magnetic material composition may also contain other components or additives as needed, as long as they do not impair the effects of this model.

[0175] <Phosphorus compound-coated rare earth-iron-based magnetic powder for high-frequency applications> The high-frequency magnetic powder included in the ultra-high-frequency absorption magnetic material composition of this embodiment is a rare-earth-iron-based high-frequency magnetic powder (phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder) containing rare earth element R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, with at least a portion of its surface coated with a phosphorus compound.

[0176] As the phosphorus compound-coated rare earth-iron high-frequency magnetic powder included in the magnetic material composition for ultra-high frequency absorption, the same type as the phosphorus compound-coated rare earth-iron high-frequency magnetic powder included in the magnetic material composition for magnetic field amplification described above can be used. The above phosphorus compound-coated rare earth-iron high-frequency magnetic powder generally exhibits excellent magnetic field amplification characteristics in the high-frequency range (1 MHz or more and less than 1 GHz) and tends to exhibit excellent electromagnetic wave absorption characteristics (ultra-high frequency absorption characteristics) in the ultra-high frequency range (1 GHz or more and less than 1 THz).

[0177] However, when applied to magnetic material compositions for ultra-high frequency absorption, it is generally preferable that the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder does not contain α-Fe-containing regions or iron oxide-containing regions. Therefore, in the above-mentioned method for producing the phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, it is preferable not to perform the oxidation step and annealing step after the phosphorus treatment.

[0178] Furthermore, when applied to a magnetic material composition for ultra-high frequency absorption, the average particle size of the rare-earth-iron-based high-frequency magnetic powder is not particularly limited, but is preferably 0.1 μm or more and 100 μm or less, more preferably 0.1 μm or more and 50 μm or less, and even more preferably 0.1 μm or more and 10 μm or less. In one embodiment of this example, it may be more preferable that the average particle size of the rare-earth-iron-based high-frequency magnetic powder be 0.1 μm or more and 5 μm or less. If the average particle size of the rare-earth-iron-based high-frequency magnetic powder is less than 0.1 μm, the amount of magnetic powder filling in the molded body becomes small, which may cause the ultra-high frequency absorption characteristics of the resulting molded body (magnetic material composition for ultra-high frequency absorption) to deteriorate. When the average particle size of rare-earth-iron-based high-frequency magnetic powder exceeds 100 μm, the imaginary term μ'' of the complex relative permeability tends to decrease, and as a result, the electromagnetic wave absorption characteristics of the resulting molded body (magnetic material composition for ultra-high frequency absorption) may decrease. Furthermore, in the ultra-high frequency region of 1 GHz or higher, when the average particle size of rare-earth-iron-based high-frequency magnetic powder exceeds 5 μm, the imaginary term μ'' may decrease along with the decrease in the real term μ' of the complex relative permeability due to the skin effect.

[0179] Rare earth-iron-based high-frequency magnetic powders preferably have an average particle size of 0.1 μm or larger, and direct contact between the high-frequency magnetic powder particles should be avoided as much as possible. When molded, if the high-frequency magnetic powder particles come into contact with each other and become electrically conductive, a skin effect occurs on the entire conductive aggregate, resulting in an effect similar to increasing the average particle size of the rare earth-iron-based high-frequency magnetic powder, and consequently, the ultra-high frequency absorption characteristics tend to deteriorate. In particular, in the case of fine rare earth-iron-based high-frequency magnetic powders with an average particle size of 3 μm or less, the high-frequency magnetic powder particles tend to aggregate, that is, they tend to come into contact with each other and become electrically conductive. Therefore, it is preferable that at least a part, preferably all, of the surface of the rare earth-iron-based high-frequency magnetic powder according to this embodiment is coated with a phosphorus compound. In particular, when forming the ultra-high frequency absorption magnetic material composition of this embodiment into a sheet (to produce a magnetic sheet), molding methods that apply heat and pressure simultaneously, such as hot pressing or calendering, are often applied. In such cases, it is preferable that an insulating film, such as a phosphorus compound, adheres firmly to the surface of the high-frequency magnetic particles, and that even if the high-frequency magnetic particles aggregate within the molded matrix, the high-frequency magnetic particles remain electrically insulated from each other. In particular, it is preferable to coat the surface of the rare-earth-iron-based high-frequency magnetic powder with a fine and moderately soft substance such as a phosphorus compound. This makes it possible to obtain a sheet-like ultra-high frequency absorption magnetic material composition with high density, high relative permeability, and good properties by applying heat and pressure simultaneously.

[0180] <Magnetic metals and / or metal oxides> The ultra-high frequency absorption magnetic material composition of this embodiment includes a phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, in addition to a magnetic metal and / or metal oxide. Here, the magnetic metal may be an alloy, and the magnetic metal oxide may be a composite oxide. The magnetic metal and / or metal oxide are usually included in the ultra-high frequency absorption magnetic material composition in the form of powder or particles.

[0181] By introducing magnetic metals and / or metal oxides into the voids between phosphorus compound-coated rare-earth-iron high-frequency magnetic powders, while maintaining electrical insulation between the core region of the phosphorus compound-coated rare-earth-iron high-frequency magnetic powder and the magnetic metals and / or metal oxides, the demagnetizing field of the high-frequency magnetic material powder decreases, causing the real term μ' of the complex relative permeability to increase, and consequently, the imaginary term μ'' of the complex relative permeability to also increase. The presence of magnetic metals and / or metal oxides increases the volume fraction of the magnetic component, thereby improving relative permeability. However, the rate of improvement (rate of increase in relative permeability) does not increase directly in proportion to the volume fraction of the magnetic component, but rather increases hyperbolically. This is thought to be due to the decrease in the demagnetizing field. As the volume fraction of the magnetic component, including magnetic metals and / or metal oxides, increases, i.e., as it approaches 1, the rate at which relative permeability improves due to this demagnetizing field tends to increase rapidly.

[0182] Furthermore, the relative permittivity of the phosphorus compound constituting the coating portion of the rare-earth-iron-based high-frequency magnetic powder is typically around 1 to 8, which is similar to that of the resin used in bonded magnetic materials (composite materials of magnetic material and resin) described later. Therefore, a nearly homogeneous and appropriately sized capacitance is generated between the magnetic component particles (phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder, and powders or particles of magnetic metals and / or metal oxides). In addition, the rare-earth-iron-based high-frequency magnetic material constituting the core region of the phosphorus compound-coated rare-earth-iron-based high-frequency magnetic powder, which is the main component of the ultra-high-frequency absorption magnetic material composition of this embodiment, typically has an intrinsic permeability between 40 and 4000 (for example, Nd2Fe 17 The permeability of N3 is 400, and its electrical resistivity is between 100 μΩcm and 4000 μΩcm (for example, Nd2Fe 17N3 has an electrical resistivity of 400 μΩcm, and in addition to its large inductance, it also has a moderate reactance. Furthermore, among magnetic metals and / or metal oxides, for example, Ni, Fe, magnetite, and maghemite have a certain inductance. Therefore, when electromagnetic waves penetrate the ultra-high frequency absorption magnetic material composition of this embodiment from the outside, a displacement current is generated between the magnetic particles, creating a kind of resonant circuit, and a phenomenon occurs in which the invading electromagnetic waves are resonantly absorbed. As a result, the imaginary term ε'' of the complex relative permittivity is greatly improved near the resonance frequency. This phenomenon is particularly evident in the ultra-high frequency absorption magnetic material composition of this embodiment, and this resonance frequency usually occurs between 1 GHz and 1 THz. At this resonant frequency, a synergistic effect usually occurs, and a higher imaginary term ε'' of the complex relative permittivity is achieved than that of each magnetic component (rare-earth-iron-based high-frequency magnetic material, and magnetic metals and / or metal oxides) alone. In one embodiment of this design, the magnetic material composition for ultra-high frequency absorption can have excellent ultra-high frequency absorption characteristics by increasing the imaginary term μ'' of the complex relative permeability and increasing the imaginary term ε'' of the complex relative permittivity.

[0183] Examples of magnetic metals include Fe (preferably iron carbonyl), Ni, Co, Fe-Ni alloys, Fe-Ni-Si alloys, Sendust, Fe-Si-Al alloys, Fe-Si-Cr alloys, Fe-Cu-Nb-Si alloys, amorphous alloys, etc. Examples of magnetic metal oxides include spinel-type ferrites such as maghemite, magnetite, Ni-ferrite, Zn-ferrite, Mn-Zn ferrite, Ni-Zn ferrite, and Ni-Mn ferrite, as well as garnet-type ferrites and magnetoplumbite-type ferrites. In terms of further improving the ultra-high frequency absorption properties of the magnetic material composition, it is preferable that the magnetic metal and / or metal oxide added to the ultra-high frequency absorption magnetic material composition be one or more of Ni, Fe (preferably iron carbonyl), or magnetite (Fe3O4).

[0184] When applied to magnetic material compositions for ultra-high frequency absorption, the average particle size of the magnetic metal and / or metal oxide is not particularly limited, but is preferably 1 nm to 100 μm, more preferably 2 nm to 50 μm, and even more preferably 3 nm to 20 μm. If the average particle size of the magnetic metal and / or metal oxide exceeds 100 μm, the ultra-high frequency absorption characteristics may deteriorate due to the generation of eddy current losses. If the average particle size of the magnetic metal and / or metal oxide is less than 1 nm, the moldability may deteriorate. Here, an average particle size of 0.1 μm or more refers to the median diameter measured under dry conditions using a laser diffraction particle size distribution analyzer. An average particle size of less than 0.1 μm refers to the median diameter measured under wet conditions using a dynamic light scattering particle size distribution analyzer. Furthermore, in the case of magnetic material compositions (compounds, molded articles, etc.), an alternative method can be used in which the particle size of 20 or more, preferably 50 or more, powder particles representing the entire material sufficiently from microscopic images such as TEM, STEM, or SEM is measured to determine the volume particle size distribution, and then the median diameter is obtained. In the above, the average particle size can be expressed as D50, where D50 is the particle size corresponding to 50% of the cumulative value of the volume-based particle size distribution of the magnetic metal and / or metal oxide powder.

[0185] The shape of the magnetic metal and / or metal oxide is not particularly limited and may be any shape, such as spherical, plate-like, flattened, flaky, needle-like, fibrous, or amorphous. However, a spherical shape is generally preferred in order to ensure that the magnetic metal is homogeneously present at the grain boundaries of the rare-earth-iron-based high-frequency magnetic powder and is magnetically isotropic.

[0186] It is desirable that magnetic metals and / or metal oxides be as close together as possible, even if a thin insulating layer is present on their surface. In this case, the demagnetizing field becomes lower, which can increase the real term μ' of the complex relative permeability, and consequently, the imaginary term μ'' of the complex relative permeability can also be increased. Therefore, the ratio of the amount of magnetic metals and / or metal oxides to the total amount of other non-magnetic components is preferably 10 volume% or more, more preferably 25 volume% or more, even more preferably 50 volume% or more, and may even be 100 volume% in order to achieve a higher complex relative permeability.

[0187] In the ultra-high frequency absorption magnetic material composition, the content (total content) of magnetic metals and / or metal oxides is preferably 0.1 parts by mass or more and 100 parts by mass or less, more preferably 0.2 parts by mass or more and 50 parts by mass or less, and even more preferably 0.5 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the rare-earth-iron-based high-frequency magnetic powder (the entire rare-earth-iron-based high-frequency magnetic powder, including the core region, the phosphorus compound coating region, and the iron oxide-containing region on the surface). If the content of magnetic metals and / or metal oxides is 0.1 parts by mass or more per 100 parts by mass of rare-earth-iron-based high-frequency magnetic powder, the addition of magnetic metals and / or metal oxides can improve the packing density of magnetic components per unit volume and reduce the demagnetizing field. As a result, a sufficient effect is obtained to increase the real term μ' of the complex relative permeability and improve the imaginary term μ'' of the complex relative permeability. Furthermore, if the content of magnetic metals and / or metal oxides is 100 parts by mass or less per 100 parts by mass of rare-earth-iron-based high-frequency magnetic powder, the content of rare-earth-iron-based high-frequency magnetic powder in the composition is also sufficiently ensured, resulting in a composition with even better ultra-high frequency absorption characteristics.

[0188] <Resin> The ultra-high frequency absorption magnetic material composition of this embodiment may further include a resin in addition to a phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder and a magnetic metal and / or metal oxide. Similar to the magnetic material composition for magnetic field amplification, such a composite material of magnetic material and resin may be called a "bonded magnetic material composition."

[0189] Molded bodies that do not contain a resin that functions as a binder, such as compacted powders using auxiliary agents such as volatile organic solvents, are extremely brittle and are generally difficult to apply to applications such as ultra-high frequency absorption materials used in 5G+ and 6G mobile devices, which are frequently carried and subjected to many impacts. Furthermore, for example, pressure-molded compacted powders contain many air layers that penetrate the molded body, and tend to oxidize and deteriorate or become brittle and lose impact resistance when exposed to temperatures of 50°C or higher for extended periods, generally making them unsuitable for high-temperature applications. Therefore, it is preferable that molded bodies (magnetic material compositions for ultra-high frequency absorption) applied to the above-mentioned applications further contain a resin in addition to phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder and magnetic metals and / or metal oxides.

[0190] The resin included in the bonded magnetic material composition is not particularly limited and may be a thermoplastic resin or a thermosetting resin. Examples of thermoplastic resins and thermosetting resins include those similar to those exemplified as thermoplastic resins and thermosetting resins included in the magnetic material composition for magnetic field amplification described above.

[0191] The resin content in a bonded magnetic material composition (magnetic material composition for ultra-high frequency absorption) is generally preferably 0.1% by mass or more and 95% by mass or less, and more preferably 0.5% by mass or more and 75% by mass or less, depending on the application. When the resin content is 0.1% by mass or more, and more preferably 0.5% by mass or more, the impact resistance, dielectric strength, and dielectric breakdown resistance of the bonded magnetic material composition tend to improve further. When the resin content is 95% by mass or less, extreme decreases in relative permeability (the real term μ' and the imaginary term μ) of the complex relative permeability and magnetization can be suppressed, and desired ultra-high frequency absorption characteristics and high relative permeability can be ensured. Furthermore, for example, when used as an electromagnetic noise absorbing sheet with particularly excellent ultra-high frequency absorption performance, it is especially preferable that the resin content be between 25% by mass and 95% by mass. Moreover, in order to obtain particularly excellent absorption characteristics as an ultra-high frequency absorption magnetic material composition, the resin content in the bonded magnetic material composition (ultra-high frequency absorption magnetic material composition) is usually 75% by mass or less, although this may vary slightly depending on the application.

[0192] <Other ingredients / additives> The ultra-high frequency absorption magnetic material composition of this embodiment may further contain other components and additives as needed, as long as they do not impair the effects of this embodiment. Examples of other components and additives include lubricants, heat-resistant anti-aging agents / heat-resistant stabilizers, antioxidants, fillers, UV absorbers, antistatic agents, colorants, and fillers. These may be used individually or in combination of two or more.

[0193] Other components and additives that may be added to the ultra-high frequency absorption magnetic material composition as needed include, for example, those listed above as other components and additives added to the magnetic field amplification magnetic material composition. The preferred range of content of these other components and additives in the ultra-high frequency absorption magnetic material composition is the same as the preferred range of content in the magnetic field amplification magnetic material composition.

[0194] <Applications of magnetic material compositions for ultra-high frequency absorption> The ultra-high frequency absorption magnetic material composition of this embodiment is capable of ultra-high frequency absorption in an ultra-wide frequency band from 1 GHz to 1 THz, exhibits high absorption characteristics, and therefore can be suitably used in this wide frequency band. In this respect, the ultra-high frequency absorption magnetic material composition of this embodiment is distinct from magnetic materials such as uniaxial crystalline magnetic anisotropy materials like hexagonal ferrite, boride, and epsilon iron oxide, which are expected to be used as ultra-high frequency absorption magnetic materials, and which have low relative permeability (real term μ' and imaginary term μ) in a narrow bandwidth of about 10 GHz.

[0195] Specific applications of the ultra-high frequency absorbing magnetic material composition of this embodiment are not limited to those described above, but include ultra-high frequency signal and spurious emission absorbing materials applied to mobile communication devices, small mobile phone base stations and cloud base stations, and infrastructure equipment such as antennas, devices, and other equipment used in 5G (5th Generation Mobile Communication System), 5G+ (5th Generation Plus Mobile Communication System), and 6G (6th Generation Mobile Communication System); ultra-high frequency signal and spurious emission absorbing materials for equipment and devices used in ITS (Intelligent Transport Systems), Wireless HDMI (registered trademark) (Wireless High-Definition Multimedia Interface), Wireless LAN (Wireless Local Area Network), satellite broadcasting (Ka-band), etc.; and electromagnetic noise absorbing materials that mainly remove the 2nd to 7th harmonics in personal computers. Specific applications of the ultra-high frequency absorbing magnetic material composition of this embodiment include electromagnetic wave absorbing paints for applications such as EMI (Electromagnetic Interference) countermeasures for automotive radar.

[0196] <Method for producing ultra-high frequency absorption magnetic material compositions and bonded magnetic material compositions> The following describes an example of a method for manufacturing the ultra-high frequency absorption magnetic material composition according to this embodiment, particularly a bonded magnetic material composition (molded body) containing resin. However, the method is not limited to the following, and it can also be manufactured by other methods.

[0197] The compound for the bonded magnetic material composition according to this embodiment can be obtained, for example, by mixing and / or kneading phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, and a resin using a kneader. The mixing and kneading method and conditions are not particularly limited and can be appropriately selected by referring to known methods. The kneading temperature can be appropriately selected according to the type of resin used, etc., and is preferably 50°C to 300°C, for example.

[0198] For example, a compound for bonded magnetic material compositions can be obtained by mixing phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, and a thermoplastic resin in a mixer, then kneading with a constant-speed roll, and finally grinding with a pulverizer to obtain pellet-shaped compounds of a desired size (e.g., several millimeters in size).

[0199] A molded bonded magnetic material composition can be produced by molding the obtained compound using a suitable molding machine. Specifically, for example, a sheet of bonded magnetic material composition (a magnetic material composition sheet for ultra-high frequency absorption) can be produced by passing the compound for bonded magnetic material composition through a roll machine, pre-rolling it, drying the resulting sheet, stacking several sheets together, and then calendering them while adjusting the reduction ratio. For example, a pelletized compound can be rolled to a thickness of 20 μm to 200 μm, thereby obtaining a magnetic material composition sheet for ultra-high frequency absorption. In this case as well, a magnetic field can be applied during calendering to cause magnetic field orientation. Furthermore, the pre-roll molding temperature and calendering temperature can be appropriately selected according to the type of resin used, and other molding and processing conditions (including the conditions for the magnetic field orientation process) are not particularly limited and can be appropriately selected. This magnetic material composition sheet for ultra-high frequency absorption can be suitably used, for example, as a magnetic material composition sheet for ultra-high frequency absorption for mobile devices.

[0200] Furthermore, the molding method is not limited to calendering; bonded magnetic material compositions (molded bodies) can be manufactured by compression molding, injection molding, transfer molding, extrusion molding, etc. When a thermosetting resin is used as the resin, molding can be mainly performed by compression molding, transfer molding, etc. Ultra-high frequency absorption magnetic material compositions that do not contain resin can be molded by, for example, sintering. These molding conditions are not particularly limited and can be selected as appropriate. In all cases, a magnetic field can be applied during the molding process to perform magnetic field orientation.

[0201] Furthermore, the ultra-high frequency absorbing magnetic material composition according to this embodiment can be in the form of a paint (electromagnetic wave absorbing paint), as described above. The ultra-high frequency absorbing magnetic material composition in the form of a paint (hereinafter also referred to as the ultra-high frequency absorbing magnetic material composition paint) can be obtained, for example, by mixing phosphorus compound-coated rare earth-iron-based high-frequency magnetic powder, a magnetic metal and / or metal oxide, an organic solvent and / or an aqueous solvent, and a resin that functions as a binder after drying or curing. The mixing method and conditions are not particularly limited and can be appropriately selected by referring to known methods. The content of the solvent (organic solvent and / or aqueous solvent) and resin in the ultra-high frequency absorbing magnetic material composition paint is not particularly limited and can be appropriately selected according to the desired application and usage of the paint. In some cases, the ultra-high frequency absorbing magnetic material composition paint can also be made without adding an organic solvent. The resin used is also not particularly limited and can be appropriately selected according to the desired application and usage of the paint.

[0202] The coating of the ultra-high frequency absorbing magnetic material composition can be dried after application, or, if it contains a curable resin, the resin can be cured to form a coating film of the ultra-high frequency absorbing magnetic material composition. In this case as well, a magnetic field can be applied during drying or curing to cause magnetic field orientation. The application method and conditions are not particularly limited and can be appropriately selected by referring to known methods. Similarly, the drying method and conditions, as well as the curing method and conditions, are not particularly limited and can be appropriately selected by referring to known methods, depending on the type of organic solvent and resin used. [Examples]

[0203] The present disclosure will be further described by the following examples, but the present disclosure is not limited in any way by these examples.

[0204] Manufacturing Example 1 By precipitation using iron sulfate and neodymium sulfate as raw materials, phosphorus-free Nd2Fe with an average particle size of approximately 15 μm is obtained as follows. 17 We fabricated N3 high-frequency magnetic powder.

[0205] [Preparation of Nd-Fe sulfuric acid solution] 5.0 kg of FeSO4·7H2O was mixed and dissolved in 2.0 kg of pure water. Then, 0.45 kg of Nd2O and 0.70 kg of 70% sulfuric acid were added and the mixture was thoroughly stirred until completely dissolved. Next, pure water was added to the resulting solution to adjust the concentration to 0.726 mol / L for Fe and 0.106 mol / L for Nd, thus obtaining the Nd-Fe sulfuric acid solution.

[0206] [Precipitation process] The entirety of the prepared Nd-Fe sulfuric acid solution was added dropwise to 20 kg of pure water maintained at 40°C, while stirring for 70 minutes from the start of the reaction. Simultaneously, 15% aqueous ammonia was added dropwise to adjust the pH to 7-8. This yielded a slurry containing Nd-Fe hydroxide. The obtained slurry was washed with pure water, and the hydroxide was separated into solid and liquid components by decantation. The separated hydroxide was dried in an oven at 100°C for 10 hours.

[0207] [Oxidation process] The Nd-Fe hydroxide obtained in the precipitation process was calcined in air at 1030°C for 1 hour. After cooling, red Nd-Fe oxide was obtained as a raw material powder.

[0208] [Pre-treatment process] 100 g of Nd-Fe oxide obtained in the oxidation process was placed in a steel container to a thickness of 10 mm. The container was placed in a furnace, the pressure was reduced to 100 Pa, and then the temperature was raised to the pretreatment temperature of 850 °C while introducing hydrogen gas. This was maintained for 15 hours to obtain a partially oxided black powder.

[0209] [Reduction Process] 60 g of partial oxide obtained in the pretreatment process and 19.2 g of metallic calcium with an average particle size of approximately 6 mm were mixed and placed in the furnace. After evacuating the furnace, argon gas (Ar gas) was introduced. The temperature inside the furnace was raised to 1045°C and held for 45 minutes to obtain Fe-Nd alloy particles.

[0210] [Nitriding process] Next, the furnace temperature was cooled to 100°C, followed by vacuum evacuation. Then, nitrogen gas was introduced while raising the temperature to 450°C, and it was maintained at that temperature for 23 hours to produce Nd2Fe. 17 A bulk product containing N3 high-frequency magnetic powder was obtained.

[0211] [Water washing process] The lumpy product obtained in the nitriding process was added to 3 kg of pure water and stirred for 30 minutes. After standing, the supernatant was drained by decantation. This process of adding to pure water, stirring, and decantation was repeated 10 times. Next, 2.5 g of 99.9% acetic acid was added and stirred for 15 minutes. After standing, the supernatant was drained by decantation. The above process of adding to pure water, stirring, and decantation was repeated twice, followed by dehydration and drying, and then mechanical crushing to obtain Nd2Fe. 17 N3 high-frequency magnetic powder (average particle size approximately 15 μm) was obtained.

[0212] Fabricated Nd2Fe 17 Using N3 high-frequency magnetic powder, phosphorus treatment and oxidation treatment are performed as follows to coat Nd2Fe with a phosphorus compound. 17 We fabricated N3 high-frequency magnetic powder.

[0213] [Phosphorus treatment process] As the phosphoric acid treatment solution, 85% orthophosphoric acid, sodium dihydrogen phosphate, and sodium molybdate dihydrate were mixed in a mass ratio of 1:6:1, and the pH was adjusted to 2 and the PO4 concentration to 20% by mass using pure water and dilute hydrochloric acid. The Nd-Fe-N high-frequency magnetic powder obtained in the water washing step was stirred for 1 minute in dilute hydrochloric acid consisting of 1000 g of water and 70 g of hydrogen chloride to remove surface oxide film and contaminants. Then, the draining and adding of water was repeated until the conductivity of the supernatant liquid was 100 μS / cm or less, to obtain a slurry containing 10% by mass of Nd-Fe-N high-frequency magnetic powder. While stirring the obtained slurry, 100 g of the prepared phosphoric acid treatment solution was added entirely to the treatment tank, and then 6% by mass hydrochloric acid was added as needed to control the pH of the phosphoric acid treatment reaction slurry within the range of 2.0 ± 0.1, and this was maintained for 40 minutes. Next, suction filtration, dehydration, and vacuum drying were performed to obtain Nd-Fe-N-based high-frequency magnetic powder coated with a phosphorus compound.

[0214] [Oxidation process] 300g of Nd-Fe-N-based high-frequency magnetic powder coated with a phosphorus compound, obtained in the phosphorus treatment process, was subjected to heat treatment at a maximum temperature of 470°C for 8 hours, gradually increasing the temperature from room temperature in an atmosphere of a nitrogen and air mixture (oxygen concentration 4 vol%, flow rate 5 L / min), thereby oxidizing the phosphorus compound-coated Nd2Fe. 17 A high-frequency magnetic powder (average particle size approximately 15 μm) for N3 was obtained. This phosphorus compound-coated Nd2Fe was used. 17 N3 high-frequency magnetic powder is Nd2Fe 17 The N3 high-frequency magnetic powder (core region) has an α-Fe-containing region between it and the phosphorus compound coating.

[0215] Manufacturing Example 2 In the same manner as in Manufacturing Example 1, untreated Nd2Fe with an average particle size of approximately 15 μm was produced. 17 We fabricated N3 high-frequency magnetic powder.

[0216] Fabricated Nd2Fe 17 Using N3 high-frequency magnetic powder, phosphorus treatment, oxidation treatment, and annealing treatment are performed as follows to coat Nd2Fe with a phosphorus compound. 17 We fabricated N3 high-frequency magnetic powder.

[0217] [Phosphorus treatment process] A phosphorus treatment process was carried out in the same manner as in Manufacturing Example 1 to obtain an Nd-Fe-N-based high-frequency magnetic powder coated with a phosphorus compound.

[0218] [Oxidation process] 300g of Nd-Fe-N-based high-frequency magnetic powder coated with a phosphorus compound, obtained in the phosphorus treatment process, was subjected to heat treatment at 465°C for 4 hours, gradually increasing the temperature from room temperature under a mixed gas atmosphere of nitrogen and air (oxygen concentration 4 vol%, flow rate 5 L / min), thereby oxidizing the phosphorus compound-coated Nd2Fe. 17 N3 high-frequency magnetic powder (average particle size approximately 15 μm) was obtained.

[0219] [Annealing process] Following the oxidation process after phosphorus treatment, the oxidized phosphorus compound-coated Nd2Fe 17 N3 high-frequency magnetic powder is further subjected to heat treatment in an argon atmosphere, gradually increasing the temperature from room temperature to 420°C for 4 hours, resulting in an oxidation and annealing treatment of phosphorus compound-coated Nd2Fe. 17 A high-frequency magnetic powder (average particle size approximately 15 μm) for N3 was obtained. This phosphorus compound-coated Nd2Fe was used. 17 N3 high-frequency magnetic powder is Nd2Fe 17 The N3 high-frequency magnetic powder (core region) has an α-Fe-containing region between it and the phosphorus compound coating, and an iron oxide-containing region is located above (outside) the phosphorus compound coating.

[0220] Manufacturing Example 3 By precipitation using iron sulfate and neodymium sulfate as raw materials, phosphorus-free Nd2Fe with an average particle size of 4 μm is obtained as follows. 17 We fabricated N3 high-frequency magnetic powder.

[0221] [Preparation of Nd-Fe sulfuric acid solution] The solution was prepared in the same manner as in Production Example 1, so that the Fe concentration was 0.726 mol / L and the Nd concentration was 0.106 mol / L, and this was used to obtain an Nd-Fe sulfuric acid solution.

[0222] [Precipitation process] Nd-Fe hydroxide was obtained in the same manner as in Production Example 1, and then dried.

[0223] [Oxidation process] The Nd-Fe hydroxide obtained in the precipitation process was calcined in air at 1000°C for 1 hour. After cooling, red Nd-Fe oxide was obtained as a raw material powder.

[0224] [Pre-treatment process] 100 g of Nd-Fe oxide obtained in the oxidation process was placed in a steel container to a thickness of 10 mm. The container was placed in a furnace, the pressure was reduced to 100 Pa, and then the temperature was raised to the pretreatment temperature of 850 °C while introducing hydrogen gas. This was maintained for 15 hours to obtain a partially oxided black powder.

[0225] [Reduction Process] 60 g of partial oxide obtained in the pretreatment process and 19.2 g of metallic calcium with an average particle size of approximately 6 mm were mixed and placed in the furnace. After evacuating the furnace, argon gas (Ar gas) was introduced. The temperature inside the furnace was raised to 1045°C and held for 45 minutes to obtain Fe-Nd alloy particles.

[0226] [Nitriding process] Next, the furnace temperature was cooled to 100°C, followed by vacuum evacuation. Then, nitrogen gas was introduced while raising the temperature to 450°C, and it was maintained at that temperature for 23 hours to produce Nd2Fe. 17 A bulk product containing N3 high-frequency magnetic powder was obtained.

[0227] [Water washing process] The lumpy product obtained in the nitriding process was added to 3 kg of pure water and stirred for 30 minutes. After standing, the supernatant was drained by decantation. This process of adding to pure water, stirring, and decantation was repeated 10 times. Next, 2.5 g of 99.9% acetic acid was added and stirred for 15 minutes. After standing, the supernatant was drained by decantation. The above process of adding to pure water, stirring, and decantation was repeated twice, followed by dehydration and drying, and then mechanical crushing to obtain Nd2Fe.17 Magnetic powder for N3 high frequency (average particle size 4 μm) was obtained.

[0228] The prepared Nd2Fe 17 Using the magnetic powder for N3 high frequency, phosphorus treatment was carried out as follows to obtain Nd2Fe coated with a phosphorus compound 17 Magnetic powder for N3 high frequency was prepared.

[0229] [Phosphorus treatment step] The phosphorus treatment step was carried out in the same manner as in Production Example 1 except that the treatment time was changed from 40 minutes to 30 minutes, and Nd2Fe coated with a phosphorus compound was obtained. 17 Magnetic powder for N3 high frequency (Nd2Fe coated with a phosphorus compound 17 Magnetic powder for N3 high frequency; average particle size 4 μm) was obtained.

[0230] <Magnetic material composition for magnetic field amplification> Example 1 The Nd2Fe coated with a phosphorus compound prepared in Production Example 1 17 The magnetic powder for N3 high frequency, metallic Ni (average particle size 2.5 μm), and an epoxy resin which is a thermosetting resin were mixed and then kneaded to prepare a compound. The content of the Nd2Fe coated with a phosphorus compound in the compound 17 was 86% by mass, and the content of metallic Ni was 10% by mass. The obtained compound was charged into a mold and molded under a pressure of 1.4 GPa, and then heat-cured in vacuo at 150 °C for 2 hours to prepare a toroidal molded body having an inner diameter of 3.1 mm, an outer diameter of 8 mm, and a thickness of 1.78 mm.

[0231] Using this molded body, the complex relative permeability in the frequency range of 1 MHz to 1 GHz was evaluated from the inductance value obtained from a one-turn inductor-shaped test fixture by an impedance analyzer (E4991B, manufactured by Keysight Technologies). Also, from the obtained values of μ' and μ", tanδ = μ" / μ' was calculated. The frequency characteristics at 10 MHz, 50 MHz, and 100 MHz are shown in Table 1.

[0232] Example 2 The Nd2Fe coated with a phosphorus compound prepared in Production Example 117 A magnetic powder for N3 high frequency, metallic Fe (carbonyl iron: CIP) (average particle size 3 μm), and an epoxy resin which is a thermosetting resin were mixed and then kneaded to prepare a compound. The P compound-coated Nd2Fe in the compound 17 The content of the magnetic powder for N3 high frequency was 76% by mass, and the content of metallic Fe (CIP) was 10% by mass. Similar to Example 1, the obtained compound was charged into a mold and molded at a pressure of 1.4 GPa, and then heat-cured at 150 °C for 2 hours in a vacuum to produce a toroidal molded body having an inner diameter of 3.1 mm, an outer diameter of 8 mm, and a thickness of 1.78 mm.

[0233] Using this molded body, similar to Example 1, the complex relative permeability in the frequency range of 1 MHz to 1 GHz was evaluated from the inductance value obtained from a one-turn inductor-shaped test fixture by an impedance analyzer (E4991B, manufactured by Keysight Technologies). Also, from the obtained values of μ' and μ", tanδ = μ" / μ' was calculated. The frequency characteristics at 10 MHz, 50 MHz, and 100 MHz are shown in Table 1.

[0234] Example 3 The P compound-coated Nd2Fe produced in Production Example 1 17 A magnetic powder for N3 high frequency, magnetite (Fe3O4) (average particle size 0.1 μm), and an epoxy resin which is a thermosetting resin were mixed and then kneaded to prepare a compound. The P compound-coated Nd2Fe in the compound 17 The content of the magnetic powder for N3 high frequency was 93.5% by mass, and the content of magnetite was 2.5% by mass. Similar to Example 1, the obtained compound was charged into a mold and molded at a pressure of 1.4 GPa, and then heat-cured at 150 °C for 2 hours in a vacuum to produce a toroidal molded body having an inner diameter of 3.1 mm, an outer diameter of 8 mm, and a thickness of 1.82 mm.

[0235] Using this molded body, the complex relative permeability in the frequency range of 1 MHz to 1 GHz was evaluated using an impedance analyzer (E4991B, Keysight Corporation) in the same manner as in Example 1, based on the inductance value obtained from a single-turn inductor type test fixture. Furthermore, tanδ = μ" / μ' was calculated from the obtained μ' and μ" values. Table 1 shows the frequency characteristics at 10 MHz, 50 MHz, and 100 MHz.

[0236] Comparative Example 1 Phosphorus compound-coated Nd2Fe prepared in Production Example 1 17 A compound was prepared by mixing N3 high-frequency magnetic powder with an epoxy resin, which is a thermosetting resin, and then kneading the mixture. The compound contained phosphorus compound-coated Nd2Fe. 17 The content of N3 high-frequency magnetic powder was set to 96% by mass. Similar to Example 1, the obtained compound was placed in a mold, molded under a pressure of 1.4 GPa, and then subjected to a heat-curing treatment at 150°C for 2 hours in a vacuum to produce a toroidal molded body with an inner diameter of 3.1 mm, an outer diameter of 8 mm, and a thickness of 1.85 mm.

[0237] Using this molded body, the complex relative permeability in the frequency range of 1 MHz to 1 GHz was evaluated using an impedance analyzer (E4991B, Keysight Corporation) in the same manner as in Example 1, based on the inductance value obtained from a single-turn inductor type test fixture. Furthermore, tanδ = μ" / μ' was calculated from the obtained μ' and μ" values. Table 1 shows the frequency characteristics at 10 MHz, 50 MHz, and 100 MHz.

[0238] Example 4 Phosphorus compound-coated Nd2Fe prepared in Production Example 2 17 A compound was prepared by mixing N3 high-frequency magnetic powder, magnetite (Fe3O4) (average particle size 0.1 μm), and a thermosetting epoxy resin, followed by kneading. The compound contained phosphorus compound-coated Nd2Fe. 17The content of N3 high-frequency magnetic powder was 93.5% by mass, and the content of magnetite was 2.5% by mass. Similar to Example 1, the obtained compound was placed in a mold, molded under a pressure of 1.4 GPa, and then subjected to a heat-curing treatment at 150°C for 2 hours in a vacuum to produce a toroidal molded body with an inner diameter of 3.1 mm, an outer diameter of 8 mm, and a thickness of 1.28 mm.

[0239] Using this molded body, the complex relative permeability in the frequency range of 1 MHz to 1 GHz was evaluated using an impedance analyzer (E4991B, Keysight Corporation) in the same manner as in Example 1, based on the inductance value obtained from a single-turn inductor type test fixture. Furthermore, tanδ = μ" / μ' was calculated from the obtained μ' and μ" values. Table 1 shows the frequency characteristics at 10 MHz, 50 MHz, and 100 MHz.

[0240] Comparative Example 2 Phosphorus compound-coated Nd2Fe prepared in Production Example 2 17 A compound was prepared by mixing N3 high-frequency magnetic powder with an epoxy resin, which is a thermosetting resin, and then kneading the mixture. The compound contained phosphorus compound-coated Nd2Fe. 17 The content of N3 high-frequency magnetic powder was set to 96% by mass. Similar to Example 1, the obtained compound was placed in a mold, molded under a pressure of 1.4 GPa, and then subjected to a heat-curing treatment at 150°C for 2 hours in a vacuum to produce a toroidal molded body with an inner diameter of 3.1 mm, an outer diameter of 8 mm, and a thickness of 1.30 mm.

[0241] Using this molded body, the complex relative permeability in the frequency range of 1 MHz to 1 GHz was evaluated using an impedance analyzer (E4991B, Keysight Corporation) in the same manner as in Example 1, based on the inductance value obtained from a single-turn inductor type test fixture. Furthermore, tanδ = μ" / μ' was calculated from the obtained μ' and μ" values. Table 1 shows the frequency characteristics at 10 MHz, 50 MHz, and 100 MHz.

[0242] [Table 1]

[0243] Comparisons between Examples 1 to 3 and Comparative Example 1, and comparison between Example 4 and Comparative Example 2 show that for the phosphorus compound-coated Nd2Fe 17 Adding a magnetic metal (Ni, Fe(CIP)) or metal oxide (Fe3O4: magnetite) to the N3 high-frequency magnetic powder increases μ' at 10 MHz to 100 MHz, and tanδ is equal to or higher than the original, so higher efficiency can be obtained.

[0244] <Ultra-high frequency absorption magnetic material composition> Example 5 The phosphorus compound-coated Nd2Fe prepared in Production Example 3 17 The N3 high-frequency magnetic powder, metallic Ni (average particle size 2.5 μm), and an epoxy resin as a thermosetting resin were mixed and kneaded to prepare a compound. The content of the phosphorus compound-coated Nd2Fe in the compound 17 The content of the N3 high-frequency magnetic powder was 76% by mass, and the content of metallic Ni was 20% by mass. The obtained compound was charged into a mold and molded at a pressure of 1.4 GPa, and then heat-cured in the atmosphere at 180 °C for 1 hour to prepare two molded bodies. The prepared molded bodies were rectangular parallelepiped-like molded bodies with a length of 10.67 mm × width of 4.32 mm × height of 1.43 mm, and a rectangular parallelepiped-like molded body with a length of 7.11 mm × width of 3.56 mm × height of 1.56 mm.

[0245] Using the rectangular parallelepiped-like molded body with a length of 10.67 mm × width of 4.32 mm × height of 1.43 mm and the rectangular parallelepiped-like molded body with a length of 7.11 mm × width of 3.56 mm × height of 1.56 mm, the complex relative permeability and complex relative permittivity in the frequency range of 18 GHz to 40 GHz were evaluated from the S-parameter values obtained by the waveguide method using a network analyzer (N5290A, manufactured by Keysight Technologies). The frequency characteristics at 18 GHz and 40 GHz are shown in Table 2.

[0246] Example 6 The phosphorus compound-coated Nd2Fe prepared in Production Example 3 17A compound was prepared by mixing and kneading N3 high-frequency magnetic powder, magnetite (Fe3O4) (average particle size 1 μm), and a thermosetting epoxy resin. The compound contains phosphorus compound-coated Nd2Fe. 17 The content of N3 high-frequency magnetic powder was 76% by mass, and the content of magnetite was 20% by mass. Similar to Example 5, the obtained compound was placed in a mold and molded with a pressure of 1.4 GPa, and then heat-cured in air at 180°C for 1 hour to produce two molded bodies. The molded bodies produced were a rectangular parallelepiped-like molded body measuring 10.67 mm in length, 4.32 mm in width, and 1.35 mm in height, and a rectangular parallelepiped-like molded body measuring 7.11 mm in length, 3.56 mm in width, and 1.30 mm in height.

[0247] Similar to Example 5, a rectangular parallelepiped molded body measuring 10.67 mm (length) x 4.32 mm (width) x 1.35 mm (height) and a rectangular parallelepiped molded body measuring 7.11 mm (length) x 3.56 mm (width) x 1.30 mm (height) was used to evaluate the complex relative permeability and complex relative permittivity in the frequency range of 18 GHz to 40 GHz using a network analyzer (N5290A, Keysight Technologies) from S-parameter values ​​obtained by the waveguide method. The frequency characteristics at 18 GHz and 40 GHz are shown in Table 2.

[0248] Comparative Example 3 Phosphorus compound-coated Nd2Fe prepared in Production Example 3 17 A compound was prepared by mixing and kneading N3 high-frequency magnetic powder with an epoxy resin, which is a thermosetting resin. 17 The content of N3 high-frequency magnetic powder was set to 96% by mass. Similar to Example 5, the obtained compound was placed in a mold and molded under a pressure of 1.4 GPa, and then heat-cured in air at 180°C for 1 hour to produce three molded bodies. The molded bodies produced were a rectangular parallelepiped-like molded body measuring 10.67 mm in length, 4.32 mm in width, and 1.74 mm in height, and a rectangular parallelepiped-like molded body measuring 7.11 mm in length, 3.56 mm in width, and 1.71 mm in height.

[0249] Similar to Example 5, a rectangular parallelepiped-like molded body with a length of 10.67 mm, a width of 4.32 mm, and a height of 1.74 mm, and a rectangular parallelepiped-like molded body with a length of 7.11 mm, a width of 3.56 mm, and a height of 1.71 mm were used. The complex relative permeability and complex relative permittivity in the frequency range of 18 GHz to 40 GHz were evaluated from the S-parameter values obtained by the waveguide method using a network analyzer (N5290A, manufactured by Keysight Technologies). The frequency characteristics at 18 GHz and 40 GHz are shown in Table 2.

[0250] Comparative Example 4 Metallic Ni (average particle size: 2.5 μm) and an epoxy resin, which is a thermosetting resin, were mixed and kneaded to prepare a compound. The content of metallic Ni in the compound was 96% by mass. Similar to Example 5, the obtained compound was charged into a mold and molded under a pressure of 1.4 GPa, and then heat-cured in the atmosphere at 180 °C for 1 hour to prepare two molded bodies. The prepared molded bodies were a rectangular parallelepiped-like molded body with a length of 10.67 mm, a width of 4.32 mm, and a height of 1.73 mm, and a rectangular parallelepiped-like molded body with a length of 7.11 mm, a width of 3.56 mm, and a height of 1.72 mm.

[0251] Similar to Example 5, a rectangular parallelepiped-like molded body with a length of 10.67 mm, a width of 4.32 mm, and a height of 1.73 mm, and a rectangular parallelepiped-like molded body with a length of 7.11 mm, a width of 3.56 mm, and a height of 1.72 mm were used. The complex relative permeability and complex relative permittivity in the frequency range of 18 GHz to 40 GHz were evaluated from the S-parameter values obtained by the waveguide method using a network analyzer (N5290A, manufactured by Keysight Technologies). The frequency characteristics at 18 GHz and 40 GHz are shown in Table 2.

[0252] Comparative Example 5 A compound was prepared by mixing and kneading magnetite (Fe3O4) (average particle size 1 μm) with an epoxy resin, which is a thermosetting resin. The magnetite content in the compound was 96% by mass. As in Example 5, the obtained compound was placed in a mold and molded under a pressure of 1.4 GPa, and then heat-cured in air at 180°C for 1 hour to produce three molded bodies. The molded bodies produced were a rectangular parallelepiped-like molded body measuring 10.67 mm (length) × 4.32 mm (width) × 1.47 mm (height), and a rectangular parallelepiped-like molded body measuring 7.11 mm (length) × 3.56 mm (width) × 1.66 mm (height).

[0253] Similar to Example 5, a rectangular parallelepiped molded body measuring 10.67 mm (length) x 4.32 mm (width) x 1.47 mm (height) and a rectangular parallelepiped molded body measuring 7.11 mm (length) x 3.56 mm (width) x 1.66 mm (height) was used to evaluate the complex relative permeability and complex relative permittivity in the frequency range of 18 GHz to 40 GHz using a network analyzer (N5290A, Keysight Technologies) from S-parameter values ​​obtained by the waveguide method. The frequency characteristics at 18 GHz and 40 GHz are shown in Table 2.

[0254] [Table 2]

[0255] From a comparison of Examples 5-6 and Comparative Examples 3-5, phosphorus compound-coated Nd2Fe 17 By adding a magnetic metal (Ni) or metal oxide (Fe3O4: magnetite) to N3 high-frequency magnetic powder, the synergistic effect significantly improves ε'' (absorption of dielectric constant) at 18GHz to 40GHz. As a result, ε''+μ'' (absorption of dielectric constant and permeability) also improves significantly, resulting in higher electromagnetic wave absorption characteristics.

[0256] The inventions described herein may encompass, for example, the following embodiments: [1] A rare earth-iron-based high-frequency magnetic powder containing rare earth elements R (where R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, wherein at least a portion of the surface is coated with a phosphorus compound, A magnetic material composition for magnetic field amplification, comprising a magnetic metal and / or metal oxide. [2] The magnetic material composition for magnetic field amplification according to item [1], wherein the rare earth-iron-based high-frequency magnetic powder is a rare earth-iron-nitrogen-based high-frequency magnetic powder that further contains N in addition to the rare earth elements R and Fe. [3] The magnetic material composition for magnetic field amplification according to item [2], wherein the rare earth-iron-based high-frequency magnetic powder is an Nd-Fe-N-based high-frequency magnetic powder containing Nd, Fe, and N. [4] A magnetic material composition for magnetic field amplification according to any one of items [1] to [3], wherein the magnetic metal and / or metal oxide is one or more of Ni, Fe, or magnetite. [5] A magnetic material composition for magnetic field amplification according to any one of items [1] to [4], further comprising a resin. [6] A magnetic material composition for magnetic field amplification according to any one of items [1] to [5], wherein the content of the magnetic metal and / or metal oxide is 0.1 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rare earth-iron-based high-frequency magnetic powder. [7] A rare earth-iron-based high-frequency magnetic powder containing rare earth elements R (where R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, wherein at least a portion of the surface is coated with a phosphorus compound, A magnetic material composition for ultra-high frequency absorption, comprising a magnetic metal and / or metal oxide. [8] The ultra-high frequency absorbing magnetic material composition according to item [7], wherein the rare earth-iron-based high-frequency magnetic powder is a rare earth-iron-nitrogen-based high-frequency magnetic powder that further contains N in addition to the rare earths R and Fe. [9] The ultra-high frequency absorbing magnetic material composition according to item [8], wherein the rare earth-iron-based high-frequency magnetic powder is an Nd-Fe-N-based high-frequency magnetic powder containing Nd, Fe, and N.

[10] The ultra-high frequency absorption magnetic material composition according to any one of the items [7] to [9], wherein the magnetic metal and / or metal oxide is one or more of Ni, Fe, or magnetite.

[11] A magnetic material composition for ultra-high frequency absorption according to any one of items [7] to

[10] , further comprising a resin.

[12] The ultra-high frequency absorbing magnetic material composition according to any one of items [7] to

[11] , wherein the content of the magnetic metal and / or metal oxide is 0.1 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rare earth-iron-based high-frequency magnetic powder.

Claims

1. A rare earth-iron-based high-frequency magnetic powder containing rare earth element R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, wherein at least a portion of the surface is coated with a phosphorus compound, A magnetic material composition for magnetic field amplification, comprising a magnetic metal and / or a metal oxide.

2. The magnetic material composition for magnetic field amplification according to claim 1, wherein the rare earth-iron-based high-frequency magnetic powder is a rare earth-iron-nitrogen-based high-frequency magnetic powder that further contains N in addition to the rare earth elements R and Fe.

3. The magnetic material composition for magnetic field amplification according to claim 2, wherein the rare earth-iron-based high-frequency magnetic powder is an Nd-Fe-N-based high-frequency magnetic powder containing Nd, Fe, and N.

4. The magnetic material composition for magnetic field amplification according to any one of claims 1 to 3, wherein the magnetic metal and / or metal oxide is one or more of Ni, Fe, or magnetite.

5. A magnetic material composition for magnetic field amplification according to any one of claims 1 to 3, further comprising a resin.

6. The magnetic material composition for magnetic field amplification according to any one of claims 1 to 3, wherein the content of the magnetic metal and / or metal oxide is 0.1 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rare earth-iron-based high-frequency magnetic powder.

7. A rare earth-iron-based high-frequency magnetic powder containing rare earth element R (wherein R is at least one selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Sm) and Fe, wherein at least a portion of the surface is coated with a phosphorus compound, A magnetic material composition for ultra-high frequency absorption, comprising a magnetic metal and / or a metal oxide.

8. The ultra-high frequency absorbing magnetic material composition according to claim 7, wherein the rare earth-iron-based high-frequency magnetic powder is a rare earth-iron-nitrogen-based high-frequency magnetic powder that further contains N in addition to the rare earths R and Fe.

9. The ultra-high frequency absorption magnetic material composition according to claim 8, wherein the rare earth-iron-based high-frequency magnetic powder is an Nd-Fe-N-based high-frequency magnetic powder containing Nd, Fe, and N.

10. The ultra-high frequency absorption magnetic material composition according to any one of claims 7 to 9, wherein the magnetic metal and / or metal oxide is one or more of Ni, Fe, or magnetite.

11. The ultra-high frequency absorbing magnetic material composition according to any one of claims 7 to 9, further comprising a resin.

12. The ultra-high frequency absorbing magnetic material composition according to any one of claims 7 to 9, wherein the content of the magnetic metal and / or metal oxide is 0.1 parts by mass or more and 100 parts by mass or less per 100 parts by mass of the rare earth-iron-based high-frequency magnetic powder.

Images